Text

Response to Request for Additional Information Regarding Steam Generator Tube Inspection Summary for Fall 2003 Outage
	ML042670416
Person / Time
Site:	Millstone
Issue date:	09/23/2004
From:	Hartz L; Dominion Nuclear Connecticut
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	04-333, FOIA/PA-2005-0210
	Download: ML042670416 (36)
	v • d • e

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Dominion Nuclear Connecticut, Inc.

Iclillstonc I'owcr Station borninion 4 Ilope Fur). I < o d W~ilrci-ford.C?' 06385 September 23,2004 U.S. Nuclear Regulatory Commission Serial No.04-333 Attention: Document Control Desk MPSLicNVDB R2 Washington, DC 20555 Docket No. 50-336 License No. DPR-65 STEAM GENERATOR TUBE INSPI In letters dated November 5, 2003, and February 26, 2004, Dominion Nuclear Connecticut, Inc. (DNC) submitted to the U. S. Nuclear Regulatory Commission (NRC) the fall 2003 refueling outage steam generator tube plugging and inspection summary reports for Millstone Power Station Unit 2.

In a letter dated June 1, 2004, the NRC requested from DNC additional information required to complete the evaluation of the submitted reports.

Attachment 1 of this letter provides the response to the request for additional information.

If you have any questions or require additional information, please contact Mr. Paul R. Willoughby at (804) 273-3572.

Very truly yours, L...

Leslie N. Hartz Vice President - Nuclear Engineering Attachment Commitments made in this letter: None.

Serial No.04-333 SG Tube Inspection RAI Response Page 2 of 2 cc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 Mr. V. Nerses Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8C2 Rockville, MD 20852-2738 Mr. S. M. Schneider NRC Senior Resident Inspector Millstone Power Station

Attachment 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING STEAM GENERATOR TUBE INSPECTION

SUMMARY

FOR FALL 2003 OUTAGE Millstone Power Station Unit 2 Dominion Nuclear Connecticut, Inc. (DNC)

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 1 of 8 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING STEAM GENERATOR TUBE INSPECTION

SUMMARY

FOR FALL 2003 OUTAGE In letters dated November 5, 2003, and February 26, 2004, Dominion Nuclear Connecticut, Inc. (DNC) submitted to the U. S. Nuclear Regulatory Commission (NRC) the fall 2003 refueling outage steam generator tube plugging and inspection summary reports for Millstone Power Station Unit 2.

In a letter dated June 1, 2004, the NRC requested from DNC additional information required to complete the evaluation of the submitted reports.

Below is the response to the request for additional information.

Question Number 1 The steam generators (SGs) at Millstone Power Station Unit 2 (MPS2) were replaced in 1993 with SGs designed and fabricated by Babcock and Wilcox International. In several locations, the reports reference tube support structures (e.g., 01H) and tube locations (e.g., Row 140 Column 79). In order for the staff to better understand the location of the indications, provide a schematic of the MP2 SGs, which depicts the tube support naming conventions. In addition, provide the following general design information: tube manufacturer, tube support (including fan bar) thickness, Fan Bar Material (e.g., Type 410 Stainless steel), and the radius of the smallest radii tube. In addition, discuss whether measurements from a tube support are from the middle of the support or the edge of the support (e.g., does F02 minus 0.6 inches specify an indication 0.6 inches from the bottom edge of the second fan bar).

Response

Excerpts from the Unit 2 Steam Generator Eddy Current Data Analysis Reference Manual are provided in Appendix A. These excerpts provide the general design information and analysis guidance for locating indications.

a Steam Generator Design a Steam Generator Tube Measurements a Location of Fan Bar Contact Points in Each Row a Steam Generator Tube Support Location Measurements a Steam Generator Dimensions a Steam Generator Arrangement a Lattice Grid Structure (Supports 2-7) a Lattice Grid Structure (Supports 1) a Fan Bar Support to Tube Interface Hot Leg Tubesheet Map Layout of Crossover Tubes (Row 1-3)

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 2 of 8 0 Tube to Tubesheet Interface 0 Steam Generator Tubes Plugged Reference Indication to Structure (9.6.16 - 9.6.18) 0 Illustration of Flaw Locations The following specific information is provided as requested:

0 Tube Manufacturer: Valinox 0 Tube Support (Including Fan Bar) Thickness: 0.1 inch 0 Fan Bar Material: Type 410 SS 0 Radius Of The Smallest Radii Tube: 3.905 inches 0 Measurements From Supports: Indication locations are referenced from the center of the tube supports, top-of-tubesheet, or the tube end, as appropriate.

They are identified in a positive direction from the closest lower structure (including tube end) unless located within two inches of the top-of-tubesheet, the center of a lattice grid support, or the center of a fan bar support. In these cases, the indications are reported from the centerline of the structure in the positive or negative direction as appropriate. A tubesheet minus measurement may be used where no tube end was recorded. See Appendix A Reference Indication to Structure (9.6.16 - 9.6.1 8).

Question Number 2 A few tubes were reported with dent and ding indications. Please clarify your reporting threshold for dents and dings and discuss whether the calibration procedure (for measuring the size of the dents and dings) is consistent with that described in Generic Letter 95-05 (or with industry guidelines). Also, discuss whether the dents and dings found during Refueling Outage 15 (R15) inspections were traceable back to your baseline inspection and discuss any changes in magnitude. If the dents and dings are not traceable to your baseline inspection and/or have changed in magnitude, discuss the reason for any change. Please discuss the results of any rotating probe inspection at dents and dings, including any anomalies.

Response

Calibration The detection of dents and dings is performed during the bobbin probe inspection. That technique is performed in accordance with Examination Technique Specification Sheet (ETSS) 1, Bobbin Standard ASME Code Examination for Parent Tubing, which is a part of the Unit 2 Steam Generator Eddy Current Data Analysis Reference Manual.

The calibration for this technique, which is identified within the ETSS, is equivalent to the applicable EPRl ETSS (i.e., 96008.1),and is consistent with EPRl Technical Report,

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 3 of 8 Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6 (industry guidelines).

Reportinq Threshold The reporting threshold used for dents and dings at MPS2 during R15 was three volts peak-to-peak. Although the MPS2 R15 threshold was three volts peak-to-peak, recent changes implemented at Millstone Power Station have revised the criteria. For any hot leg indication greater than three volts peak-to-peak, the Motorized Rotating Pancake Coil (MRPC) will be reused with a reporting threshold of two volts peak-to-peak. This threshold will be utilized at MPS2 during Refueling Outage 16 (R16).

R15 Dents and Dinqs During R15 eight thousand five hundred and twenty-three (8523) bobbin examinations were performed. Of that, twenty-two dentddings were identified in twenty tubes or 0.26% of the tubes. Identification of dents and dings has been widely experienced throughout the industry, although previous experience did not receive the current level of attention. The recording criteria, which has been utilized at MPS2 for the past several outages has included the incorporation of industry operating experience (i.e.,

OE). This operating experience has resulted in revisions to the dent and ding analysis flow charts to support the detection of Outside Diameter Stress Corrosion Cracking (i.e.,

ODSCC) within dents or dings.

MPS2 reported 22 dents and dings during R15. Most of these indications were directly traceable to baseline indications. Although comparisons of the voltage are provided, as requested, a change in magnitude is not necessarily relevant or even comparable.

Sixteen of the twenty-two reported indications have decreased in amplitude since their discovery. Two of the remaining six indications were first identified in R15 and were slightly above the reporting criteria. The four remaining indications have increased 0.21, 0.33, 0.7, and 0.77 volts since the time of discovery.

There are many possible reasons why the remaining six indications were not identified in the baseline and/or why changes exist in the baseline voltage amplitude. These are:

Testing equipment and techniques have changed and/or significantly improved since 1991.

a Distance changes between the inspection coils and tube wall due to probe diameter. The baseline examinations at MPS2 were performed using 0.600-inch probes, whereas the R15 examinations utilized 0.610 inch probes for better fill factor. This results in a change in diametral offset of the probe.

The qualified techniques per Appendix H, Performance Demonstration for Eddy Current Examinations of EPRI Technical Report, Pressurized Water Reactor

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 4 of 8 Steam Generator Examination Guidelines: Revision 6, have increased detectability.

. More attentiordscrutiny is paid to dents and dings in the industry today than during examinations performed in the 1991 timeframe. Consequently, there were fewer MRPC examinations performed during the baseline examinations.

. The current Millstone procedure methodology for establishing calibration sensitivity is consistent with the current industry guidelines. The current sensitivity is established by setting the 4 x 20% flat-bottom holes equal to four volts peak-to-peak. However, the calibration sensitivities for the baseline examination were established by setting the 4 x 100% through-wall holes equal to six volts peak-to-peak. This difference accounts for some voltage differences.

. In 1991, MPS2 performed a 100 % baseline examination of both steam generators, prior to their installation in the plant. At the time of examination the steam generators were in a horizontal position. Due to gravity the location of the bobbin probe would be at the bottom of the tube. This would increase the distance between the inspection coils and the upper tube wall, which would not occur when the steam generator was installed vertically (i.e., diametral offset of the probe within the tube). The significance is that an indication on the top of the tube (with the tube in a horizontal position) would be farther away from the coil due to gravity. Also, as the positioning tangs on the probe wore (i.e., bottom tangs got shorter), the coil would drift even farther away from an indication. As the distance increases between the coil and indication, the voltage amplitude decreases. Consequently, when the steam generator was installed vertically, the exact same size indication will provide a much larger voltage (indicating significant growth) due to probe proximity (i.e., probe is now centered vs. on bottom of tube).

Appendix B, Ding/Dent Indications, Steam Generator No. 2, reviews each tube reported with a dent or ding during R15. Also, the trending information section identifies when the indication was found, initial voltage amplitude, R15 voltage amplitude, any Rotating Pancake Coil (RPC) testing and results, and possible explanations for changes in the voltage amplitude changes.

Rotatinq Probe Results The higher temperature/susceptibility of dents in the hot leg will likely lead to cracking prior to the cold leg and U-bend dents. Consequently, all the hot leg dents and dings are monitored (i.e., have been tested with the RPC at least twice since initial discovery).

All the RPC examinations were classified as No Degradation Detected (NDD) or No Degradation Found (NDF).

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 5 of 8 Question Number 3 A few tubes were reported to have a possible loose part indication (PLP). Some of the tubes with these indications are in the interior of the tube bundle. Please clarify whether the tubes with PLP signals were visually inspected to confirm the nature of these PLPs.

If visual inspections were not performed and/or if the part was not remove, discuss what analyses were performed to ensure these PLPs do not compromise tube integrity for the period of time between inspections.

Response

During R15, eddy current testing identified five PLPs with indications of damage just below the first support plate interior to the tube bundle. These locations are identified on Table 1, Tubes with Loose Parts and Indications Identified in 2R15.

Table 1-Tubes with Loose Parts and Indications Identified in 2R15 Row Col SG Part Percent Support Identifier Inches from Removed Throughwall Support Center 28 5 2 Yes 23 01c -2.44 59 10 2 Yes 21 01c -6.69 123 46 2 Yes 20 01H -6.57 125 48 2 Yes 24 01H -4.96 126 I 49 I 2 1 Yes 24 01H -4.47 A remote visual inspection was performed at each location identified in Table 1. These inspections confirmed the presence of foreign material at each identified location (i.e.,

just below the first support plate). The Foreign Object Search and Retrieval (FOSAR) team removed all the foreign material at these locations. Seven segments of flexitallic gasket ranging from approximately 4 inches to 14 inches long were removed. During the in-bundle visual inspection, four new locations were identified with irretrievable flexitallic gasket. However, the flexitallic gasket was located on the tube sheet.

Historical experience has shown that material in-bundle and on the tubesheet does not damage the tubes. These four locations are included on Table 2, Foreign Material Remaining in Steam Generators. All irretrievable foreign material identified and remaining in either steam generator to date is identified in Table 2.

In addition to the above PLPs, the R15 eddy current examination identified other PLP signals with no indication of degradation. These indications were located slightly above the top-of-tubesheet on the hot side. All these PLPs had been previously identified and evaluated during R13. The R15 eddy current testing determined that degradation did not exist at these locations. Consequently, R15 testing confirms a zero wear rate for these locations. This is identified in Table 2.

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 6 of 8 Table 2- Foreign Material Remaining in Steam Generators Foreign Identified Location Est. Size % Comments Object Evaluation Indication SG Row I Column Flex R13 2 R50, C7 - 4 x 1/4 x 0.013 0 No indication CR-00-1234 R52, C7 rf15 Wear rate = 0 Flex R13 2 R44, C85 - 4 x 114 x 0.013 No indication CR-00-1234 R46, C86 rf15 Wear rate = 0 Weld R13 2 R27, C20 118 dia x 5 No indication Rod CR-00-1234 R26, C21 rf15 R29, C20 Wear rate = 0 R28, C21 Weld R13 2 R94, C129 118 dia x 8 No indication Rod CR-00-1234 R96, C129 rf15 R98, C129 Wear rate = 0 R100, C129 R102, C129 R93, C130 R95, C130 R97, C130 R99, C130 R101, C130 R101, C130 Weld R13 2 R45, C36 118 dia x 5 0 No indication Rod CR-00-1234 R46, C37 RF15 R47, C36 Wear rate = 0 Spacer R13 2 R93, C40 118 inch nut, No indication CR-00-1234 R94, C139 -1.5 long RF15 R95, C140 Wear rate = 0 Weld R14 1 R24, C101 1 . 5 x 318x 118 Stainless steel.

Slag CR-02-01863 Cold R23, C102 Present since R24, C103 1994 per ECT R25, C102 Wear rate = 0 Flex R15 2 R32, C5 - 4 x 114 x 0.013 CR-03-10511 Hot R33, C4 R34, C5 Flex R15 2 R133, C110 - 4 x 1/4 x 0.013 CR-03-10511 Hot R132, C111 Flex R15 2 R123, C122 - 4 x 114 x 0.013 0 CR-03-10511 Hot R123, C121 Flex R15 2 R134, C109 -4 x 114 x 0.013 0 CR-03-10511 Hot R135, C108 Screw R13 1 #6, 518, 1.19 oz 0 Very small CR-00-1223 screw, fell out of Snapon ratchet.

Location unknown

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 7 of 8 Question Number 4 Several tubes were identified that have bulges. Please discuss whether these indications were in the baseline inspection and discuss any changes in size, discuss the reason for any changes. If the bulges are not traceable to your baseline inspection and/or have changed in size, discuss the reason for any change. Please discuss whether these indications were inspected with a rotating probe.

Response

Table 3 addresses the bulges identified during R15.

Table 3- Bulges Identified During R15 R15 1991 Baseline Indication Row Col. Indication Voltage Location Indication Voltage Location Reported Notes 80 31 BLG 4.68 07H BLG 7.21 H07 Yes 172 9 34 BLG 3.12 TSH No 293 2 35 BLG 4.59 07H No 2 Notes 1 Tested with RPC during Preservice.

2. Tested with RPC during R15. No degradation found.

3. R15 voltage is slightly greater than the reporting voltage 3 volts. The reported voltage is well within the uncertainties established for eddy current testing.

During the baseline examination, calibration sensitivities were established by setting the 4 x 100% through-wall holes equal to six volts peak-to-peak. Currently, for bobbin examinations, voltage normalization is accomplished utilizing the primary differential channel on the four 20% flat bottom holes of the ASME standard, with a normalized peak-to-peak voltage of four volts. These calibration differences alone could be what raised the voltage slightly above the reporting criteria for tube R9 C34. Other possible explanations for the amplitude changes include (but are not limited to):

. Changes and significant improvements in testing equipment techniques since 1991.

. Steam generator position during examination (e.g., horizontal vs. vertical)

. Distance changes between the inspection coils and tube wall due to probe diameter (i.e., the baseline examinations were performed using 0.600 inch probes, whereas the R15 examinations utilized 0.610 inch probes for better fill factor).

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Page 8 of 8 Different diametrical offset of the probe within the tube, and

. Probewear.

Question Number 5 Please clarify the number of tubes in each of the two SGs and discuss whether any tubes were plugged prior to commercial operation.

Response

During the construction of Steam Generator 1, a drill bit broke while drilling the hot leg tubesheet at location R57 C156. As a result of the associated damage, that hot leg location was plugged and the associated cold leg hole was never drilled. Currently this plug is the only plug in either steam generator. (See Appendix A, Reference Manual Excerpts, Page 40, Steam Generator Tubes Plugged). Consequently, Steam Generator 1 has 8522 active tubes and Steam Generator 2 has 8523 active tubes.

Question Number 6 In your report you indicate that tube-to-tube contact occurs primarily in the tube U-bends and is caused from tube bowing between supports. Please discuss whether any tube-to-tube contact has been observed at MP2. Please discuss whether the number of tubes affected has increased/decreased since the SGs were installed. If tube-to-tube contact is occurring, please discuss the effects on the eddy current inspection including the ability to detect loose parts.

Response

To date no tube-to-tube contact has been identified in either steam generator.

Attachment 1 Appendix A MILLSTONE POWER STATION UNIT 2 STEAM GENERATOR EDDY CURRENT DATA ANALYSIS REFERENCE MANUAL EXCERPTS Millstone Power Station Unit 2 Dominion Nuclear Connecticut, Inc. (DNC)

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix A / Page 1 of 16 Millstone Power Station Unit 2 Steam Generator Eddy Current Data Analysis Reference Manual Excerpts The following pages have been excerpted from U2-24-SIP-REF01 Unit 2 Steam Generator Eddy Current Data Analysis Reference Manual.

Reference Manual Paqe Steam Generator Design 14 of 200 Steam Generator Tube Measurements 15 of 200 Location of Fan Bar Contact Points in Each Row 16 of 200 Steam Generator Tube Support Location Measurements 17 of 200 Steam Generator Dimensions 18 of 200 Steam Generator Arrangement 19 of 200 Lattice Grid Structure (Supports 2 - 7) 20 of 200 Lattice Grid Structure (Support 1) 21 of 200 Fan Bar Support to Tube interface 22 of 200 Hot Leg Tubesheet Map 23 of 200 Layout of Crossover Tubes (Row 1 - 3) 24 of 200 Tube to Tubesheet Interface 25 of 200 Steam Generator Tubes Plugged 40 of 200 Reference indication to Structure (9.6.16 - 9.6.18) 54 of 200 Illustration of Flaw Locations 62 of 200

3t.C.

5. STEAM GENERATOR DESIGN Millstone Unit 2 is a Combustion Engineering two-loop pressurized water reactor with replacement SGs manufactured by Babwk and Wilcox Canada. Each SG was designed to contain 8,523 U-bend,thermally treated limnel 690 tubes. The SG primary head divider plate divides the head into two separate plenums. The plenums are identified as hot leg (inlet) and cold leg (outlet). ?he SG arrangement is shown in Figure 5-1.

Secondary side tube Suppcxt structures include seven lattice grid supporh in the straight leg section of the tubes, and twelve fanbar assemblies in the U-bend section of the tubes.

Measurements of the straight tube portion of the support structure are provided in Table 5-1. All lattice grid supports are full supports. The lattice grid for Support 1, shown in Figure 5-3, is made up of high bm (3.15 inch wide), medium bars (2.562 inch wide) and low bars (1.00 inch wide). The lattice gdd for Supports 2 through7, shown in Figure 5.2, is made up of high bars and low bars. Table 5-2 and Figure 5-4provide the relationship between the fan bar assemblies and rows of tubes. The fan bars are of various widths and the two fan bars at a given tubdfan bar intersectian are offset from one another. This offsetdistance varies from one fanbar to another.

The tubesheet is drilled on a triangular, linch pitch. Each tube is identified by a line and row number. There are 167 lines and 141rows in each SG. figure 5-5 shows a hot leg tube sheet map. To minimize small radius bends the origin and tamination of tubes in rows 1 through 3 differ between the hot leg and cold leg. Figure 5-6 shows the relationship between hot leg ori@n and cold leg termination for rows 1 through 3. Tube identification is taken from the hot leg location.

The tubes are hydraulically expanded over the full depth of the tubesheet. The tubing is nominal 0.750 inch outside diameter with a 0.0445 inch nominal wall thickness. The tubing was produced using a pilgetine process which generates minor geometryvariations on the ID surface.

figure 5-7 shows the nominal dimensions of a tube-to-tubesheet expansion region. Table 5-3 shows the location of the tube supports along the tube length. Various SG dimensions are provided in Table 5-4.

3 Unit 2 Stcam Genembr Eddy Cmmt W2-24-SIP-RBWl Data Aaalysls Reference Manual L4of 200 ' Rm.002

I Table 5-1 Steam Generator Tube Measurements Millstone Unit 2 I Unit 2 Steam h e r a t o r m y current Data Analysis Referne Manual IS of 200 U2-24-sIP-RRFOI Rev. 002 I

Table 5-2 Location Of Fan Bar Contact Points In Each Tube Row Millstone Unit 2 Steam Generators FAN BAR CONTACT POINTS I Unit 2 Stcam enerstor eday Cumnt U2-24-sIP-REIM)I M a Analysis Reference Manual 16 of 200 Rev. OD2

~ - -~

Table 5-3 Stesm Generator Tube Support Location Measurements Mistone Unit 2 Location inches FromTube End Center to Center Set Scale Spacing Tube End 0.00 TOQOfTrvbesheet 22.25 22.2s 22.3 R1 LatticeGrW 46.25 24.00' 24.0

2 LaUke Grid 81275 35.1 28 35.1

a Lattice &id 123.0 41.625 41.6 WtamOeGitid 164.%25 41.625 41.8

5 Lattice Qrid 206.26 41.6s 41.6 v #6 Latttce Gdd 247.876 41.625 41.6

7 Lattice Gdd 2895 41.625 41.6

Measurement from top edge of tubesheet to center of # Lattice l Grid.

Unit 2 Steam [kacratot eddy Current U2-24-S1P-REFOl Data Analysis Refmcc Mmual 17 of 200 Rev. 002

c Table 5-4 Steam Generator Dimensions Millstone Unit 2

-~

MLLSTOMEUNIT 2 STEAM GENERATOR DIMIIENSIONS Wnber of Tubes 8528 rube Material: Jnconel890 Thermally Treated XI of Tubes: 0.7W rube Wall Thtokness 0.W' vumberof Lattice QrkJsupports: 7 Lattice GrId Material: Type 410 SS Vuumberof Fan Bar AssernMies: 12 Fan Bar Material Tvps 410 SS Fan BarThickness 0.1 12" Fan Etar Wldth Various (l,oCr, 2.58T, 3.15")

rubesheet mckness 21.76' Expansion Methad Hydraulic Extent of mansion Full through Tubesheet Tube Qitdl 1.O' Row 1 Radius 4.272' Row 3 Raaus {Smalrest Fladius) 3.9059 Worn Tube Sheet Claddlng 182 Cfad Thickness 0.31' Tube End Location O W Belaw Bottom d Tubesheet Unit 2 SteamGenecamEddy Current U2-24.SIP-REFOl Data AnaiySis Referencehnzanual 18of200 Rev. OM

.. ~ :.

I I Fignre 5-1 Millstone Unit 2 Steam Generator Arrangement 7

s

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I Unit 2 Stam Generator Eddy Cumnt Data Analysis Reference Manual 19 of200 U2-24-SIP-REFOI Rev. 002

Figm 5-2 Lattice Grid Structure (Supports 2 through 7) 1: .,.. , .

Unit 2 Sttam Oenatltor Eddy (=wrent Date Analysis Rcfuence M&d 20 of 200 Rev. 002 I

Figure 5-3 Lattice Grid Structure (Support 1)

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......~..: .-? .Unit 2 Steam aemratorEddy Current 212-24-sXp-rn1 Data Analysis Rcfenm Manual 21 of200 Rev. OM

I Figure 5-4 Fan Bar Support to Tube Interface F061 12

Figure 5-5 Hot Leg Tubesheet Map Unit 2 Stem Generutor Eddv cum*

I --------

Data Analysis Referrnce Menual

-I 23 of200 U2-24-SIP-REiP01 Rev. OM

Figure 5.6 Layout of Crossover Tubes (Row1 to 3)

Viewed From Primary Side

Figure 5-7 Tube to Tubesheet Interface Unit2 StcamaeneratotEddycUmnt 1 Data Analysis Refmnce Manual 2!iOf200 U2-24-$IF-RBFOI Rev. 002

Table 6-10 Steam Generator Tubes Plugged Mitistone Unit 2 SQ# ROW Une %w LOColtiOn Vdts Reason Fabrtcatkn 1 87 I58 Broken Drill Bit fp~ugg hot

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side only; cold side not drirled) uni12 steam ckmrator l?ddy c u m U2-24-sIP-REFOI Data Analysis Reference Menual 40of 200 Rev.002

9.6.12 Volt Peab-ta-Peak is the p r e f d phase angle measurement. For cases where no clear transitionexists, a VoitS Peak-@Peak measurement shall be used. Volts Max Rate may be used for signals having a well-defined transition. Guess h g l e may only be used by the Resolution or Senior Analysts and only when the latter two methods do not give a good representation afthe signal phase angle.

9.6.13 Tube to tube contact (or tubes in close proximity) with a voltage equal to or greater than S volt vett max shall have a from-to location and a vert max voltage measurement made from the 130 kHz absolute channel (CH 6).

9.6.14 AU indications of tube wall degradation which can be sized, must be sized, and the through wall deptb and axial location shall be reported. Those which cannot be sized shall be reported as an I-Code.

9.6.15 For all indications greater than or equal to 20%through wall and "I" codes,a reevaluation of previous examination data shall be performed.

9.6.16 Indication locations shall be referenced fromthe center of the tube suppoas, top-of-tubesheet, or tube end, as appropriate. The analyst shall refer to Figure 5-4 when refmncing the fan bar number, which is dependent upon the tube row number.

9.6.17 All indication locations shalt be measured in a positive direction h m the

/ closest lower structure (including tube end), except as folIows:

a. Those indications located within 2.0 inches of the top-of-tubesheet, center of a lattice grid suppOa,or center of a fan bar support shall be reported from the centdine of the structure in the positive (+)

or negative (-) direction, as applicable.

b. A tubesheet minus measurement (is., TSH -5.50) may be reported in cases where no tube end was recorded 9.6.18 The positive direction forreporting indication locations is in the direaim from lattice grids, fan bars, tubesheet and tube mds toward the top cold leg support (07C). The sign commation changes at the tube location 2.00 inches above the centerhe of tub support 07C. The convention for reportingflaw locations is shown in Figure 5-1, with s p d i c examples shown in F5guce 9-2.

9.6.19 A six character Test Extent shall be reported. Test Extent shall be I reported as actual begin test (3-1elter location) and actual end test (3-letter IoCation). In the case of only one intersection Wmg tested, the begin and the end test will be that intensection (Le., 07H07H).

Unit 2 S t a m Generator E!ddy Current I Data A~lyafs Reference Manual 54 of 200 U2-24-SlP-RBK)l Rev. 002

.F'igum 9-2 lllwtration of Flaw Locations F12 +4.W 07C + 1.W' LOCATION OF' SIGN COMENnON CHANGE LOCAtlON OF SIGN 0 CONVENTION CHANGE 1

- 07C-1.86"

\

Unit 2Sieam Ocnmtor Eddy Cumnt U2-24-SIP-rn1 Data Analysis R e f m e Manual 62 of 200 Rev. OM

Attachment 1 Appendix B MILLSTONE POWER STATION UNIT 2 DNG/DNT INDICATIONS, STEAM GENERATOR 2 Millstone Power Station Unit 2 Dominion Nuclear Connecticut, Inc. (DNC)

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix B / Page 1 of 7 MILLSTONE POWER STATION UNIT 2 DENT AND DING INDICATIONS, STEAM GENERATOR 2 Dent/Ding Trending Information Tube First reported in the pre-installation baseline examination, this cold 1-10 leg indication has changed from 22.48 Volts to 12.35 Volts along with the call channel changing from a process channel, (mix of two Location frequencies), to a single prime frequency differential channel. The 04C+32.29 current procedure methodology for establishing calibration sensitivity is consistent with the industry guidelines, (4~20%flat-bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Tube First reported in the pre-installation baseline examination, this hot 1-116 leg indication has only varied from 6.35 Volts to 5.29 Volts despite the call channel changing from a process channel, (mix of two Location frequencies), to a single prime frequency differential channel. The 04H+32.30 current procedure methodology for establishing calibration sensitivity is consistent with the industry guidelines, ( 4 ~ 2 0 %flat-bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

RPC tested R11 and R15 with no degradation found (NDF).

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix B / Page 2 of 7 Dent/Ding Trending Information Tube First reported in the pre-installation baseline examination, this 1-116 indication has only varied from 8.55 Volts to 6.76 Volts despite the call channel changing from a process channel, (mix of two Location frequencies), to a single prime frequency differential channel. The 03H+34.77 current procedure methodology for establishing calibration sensitivity is consistent with the industry guidelines, (4~20%flat-bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

RPC tested R11 and R15 with no degradation found (NDF).

Tube This small U-bend ding (7.04 Volts) was first detected in mid-cycle 4-61 inspection (i.e., 1997) with a voltage of 11.50. Possible explanations for the amplitude changes include (but are not limited Location to); distance changes between the inspection coils and tube wall F01+11.64 due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Tube First reported in the pre-installation baseline examination, this 23-4 U-bend indication has only varied from 3.36 Volts to 3.5 Volts. The current procedure methodology for establishing calibration sensitivity Location is consistent with the industry guidelines, (4~20%flat-bottom holes F05 -1.1 9 equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix B / Page 3 of 7 Dent/Di ng Trending Information rube First reported in the pre-installation baseline examination, this 24-3 U-bend indication has only varied from 4.18 Volts to 3.48 Volts.

The current procedure methodology for establishing calibration Location sensitivity is consistent with the industry guidelines, ( 4 ~ 2 0 %flat-F05 -1.63 bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4~100%through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Tube This small hot leg ding (4.59 Volts) was first detected in 2R13 (i.e.,

50-79 fall 2000) with a voltage of 4.83. RPC was performed of this indication in both outages. There was no detectable degradation Location found (NDF).

04H+31.30 RPC tested R13 with no degradation found.

RPC tested R15 with no degradation found.

Tube This small hot leg ding (3.89 Volts) was first detected in 2R13 (i.e.,

54-33 fall 2000) with a voltage of 4.03. RPC was performed of this indication in both outages. There was no detectable degradation Location found (NDF).

07H-0.17 RPC tested R13 with no degradation found.

RPC tested R15 with no degradation found.

Tube First reported in the pre-installation baseline examination, this 61-56 U-bend indication has varied from 16.87 Volts to 9.1 1 Volts despite the call channel changing from a process channel, (mix of two Location frequencies), to a single prime frequency differential channel. The F03-1.60 current procedure methodology for establishing calibration sensitivity is consistent with the industry guidelines, (4~20%flat-bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x1 00% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix B / Page 4 of 7 Dent/Ding Trending Information Tube First reported in the pre-installation baseline examination, this 61-62 U-bend indication has varied from 7.61 Volts to 6.11 Volts despite the call channel changing from a process channel, (mix of two Location frequencies), to a single prime frequency differential channel. The FO1 +2.37 current procedure methodology for establishing calibration sensitivity is consistent with the industry guidelines, (4~20%flat-bottom holes equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

Tube First reported in the pre-installation baseline examination, this hot 67-44 leg indication has varied from 22.46 Volts to 17.38 Volts. The current procedure methodology for establishing calibration sensitivity Location is consistent with the industry guidelines, (4~20%flat-bottom holes TSH +13.84 equal to four volts peak-to-peak), as described in the EPRl Technical Report, Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 6. During the baseline examination, calibration sensitivities were established by setting the 4x100% through-wall holes equal to six volts peak-to-peak. Other possible explanations for the amplitude changes include (but are not limited to); distance changes between the inspection coils and tube wall due to probe diameter differences, diametrical offset of the probe within the tube, and probe wear.

RPC tested four times (i.e., 1991, 1997, 2000, and 2003) with no degradation found.

Tube This small cold leg ding (3.02 Volts) was first detected in a mid-cycle 69-38 inspection (i.e., 1997) with a voltage of 4.4. During R13 it was not reportable with a voltage of 1.97 volts. These voltage changes are Location most likely related to the distance between the inspection coil and 02C+0.97 the tube wall (i.e., probe diameter differences, diametrical offset of the probe within the tube, and probe wear).

Tube This small cold leg dent (1.82 Volts) is below the reportinghecording.

72-109 Location F09+0.47

Serial No.04-333 SG Tube Inspection RAI Response Attachment 1 / Appendix B / Page 5 of 7 Dent/Ding Trending Information Tube This small U-bend ding (3.26 Volts) was first reported in 2R15. The 88-79 most probable reason for the change is related to the distance between the inspection coil and the tube wall (i.e., probe diameter Location differences, diametrical offset of the probe within the tube, and F05+0.94 probe wear).

Tube This small cold leg ding (4.02 Volts) was first detected in 2R13 (i.e.,

92-79 2000) with a voltage of 3.69. This indication was not identified during the baseline inspection (with the steam generators in the Location horizontal position). However, the indication was present the first 04C +33.56 time this tube was tested with the steam generator installed vertically.