L-2005-234, Revised Steam Generator Tube Inservice Inspection, Special Report for Refueling Outage SL1-19 & RAI Response

Revised Steam Generator Tube Inservice Inspection, Special Report for Refueling Outage SL1-19 & RAI Response

ML053190206
Person / Time
Site:	Saint Lucie
Issue date:	11/09/2005
From:	Jefferson W Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2005-234
Download: ML053190206 (12)

Text

Florida Power & Light Company, 6501 S.Ocean Drive, Jensen Beach, FL 34957 November 9, 2005 FPL L-2005-234 10 CFR 50.55a 10 CFR 50.36 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Revised Steam Generator Tube Inservice Inspection Special Report for Refueling Outage SLI-19 & RAI Response Attached is complete replacement of the Steam Generator Tube Inservice Inspection Special Report required by sections 4.4.5.5.b and 6.9.2 of the St. Lucie Unit 1 Technical Specifications for the spring 2004 refueling outage (SLI-19) submitted by FPL letter L-2005-077 dated April 8, 2005. A portion of the report was inadvertently omitted in the original submittal.

Attachment 1 provides a revised report and Attachment 2 provides a response to the NRC request for additional information (RAI) dated July 12, 2005. A revised response date was discussed with the NRC project manager.

Should there be any questions, please contact us.

Williamn I' Vice President St. Lucie Plant WJ/GRM Attachment

.1 §C:cil an FPL Group company

I St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 1 Page 1 Replacement St. Lucie Unit I Spring 2004 Refueling Outage SLI1-19 Steam Generator Tube Inservice Inspection Special Report

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 1 Page 2 This report addresses Plant Technical Specification Section 4.4.5.5 b. The attached information provides the summarized results for the inservice examination of steam generator tubing, which is to be submitted to the Commission within 12 months of the examination completion date.

1. Inservice eddy current examination and tube plugging of the St. Lucie Unit 1 steam generators was completed between April 4, 2004 and April 10, 2004. The examination scope as noted below is represented under "Total Tubes Inspected" on the attached FORM NIS-BB, Owners' Data Report for Eddy Current Examination Results.

Examination Scope Bobbin Coil Probe

• Approximately 57% of the inservice tubes in S/G 1A and approximately 54% of the inservice tubes in S/G 1B were examined from tube end to tube end. Row 3 examinations (because of the tight bend radii) included the hot leg and cold leg straight sections with complementary u-bend examinations performed using the Plus Point Probe.

Plus Point Rotating Probe

• Approximately 50% of the hot leg Expansion Transitions from 3 inches above to 2 inches below the secondary face of the tubesheet.

• 50% of the row 3 U-bends as a minimum were examined. (Row 3 has the tightest bend radius due to the crossover design)

• Special interest (diagnostic) locations as required by the bobbin coil results.

2. The location and percent of wall thickness penetration is also summarized on the attached FORM NIS-BB under "Location of Indications. To date, no corrosion type indications have been reported at St. Lucie Unit 1.

3. Three (3) tubes were preventively plugged in S/G 1A due to mechanical wear that was less than the Technical Specification plugging limit of 40% wall thickness penetration.

This is summarized in the upper portion of the attached FORM NIS-BB.

4. A total of 21 mechanical wear indications (17 in S/G 1A and 4 in S/G 1B) detected at u-bend support structures that measured less than 20% wall thickness penetration will remain in service for cycle 19.

5. The source documents (tubes preventively plugged, 20% to 39%, and 1% to 19%)

used for preparation of FORM NIS-BB are attached for reference.

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 1 Page 3 FORM NIS-BB OWNERS' DATA REPORT FOR EDDY CURRENT EXAMINATION RESULTS As required by the provisions of the ASME CODE RULES EDDY CURRENT EXAMINATION RESULTS PLANT: St. Lucie Unit I Outage: SL1-19 EXAMINATION DATE: April 4.2004 through April 10, 2004 TTLTUBES TOTAL STEAM TOTAL TOTAL TOTAL TUBES PLUGGED PLUGGED GENERATOR TUBES TUBES >4W PIT& VO PREVENTIVELY THIS TUBES INSPECTED 201/-39% PLUGGED (PTP) OUTAGE INS/G 769802A (Bobbin) 4834 3 0 3 3 14 769801B (Bobbin) 4640 0 0 0 0 0 769802A (RPC) I,) 4288 (2) 0 0 0 0 See Bobbin 769801B (RPC) (1) 4291 (2) 0 0 0 0 See Bobbin LOCATION OF INDICATIONS (1%- 100%. PIT & VOL)

U Bend Lattice Grids STEAM CBH p (TSP's) Top of Topof Total GENERATOR To 01 to 07 Tubesheet Tubesheet Indications CBC 3)to to

1. 1Support #1 Support PTo H/L CC / LH /L 1%-19% 20%-39% V0%.PITor 769802A (Bobbin) 3 0 0 0 0 17 3 (z)0 7698018 (Bobbin) 0 0 0 0 0 4 0 769802A (RPC) (1) 0 0 n rn/a n/a n/a n/a 0 769801B (RPC) t . n/a n/a n/a n/a n/a n/a 0 Remarks:

(1) RPC = Rotating Pancake Coil Technique.

(2) Includes tubes In the low row U-bend & dent programs.

(3) CBH =Connector Bar Hot Leg: CBC = Connector Bar Cold Leg (4) Tubes with indications measuring greater than or equal to 20% through wall were preventively plugged (PTP).

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 1 Page 4 The following listings are source documents used for the preparation of "Form NIS-BB".

S/G A Tubes with Bobbin 20-39% TWD Indications QUERY: QueryMl ROW LINE VOLTS DEC CHN IND %TW LOCATION EXT EXT CAL 1 LEG PROBE

.===== -= === -= -= == ... =~=====

... === === ====

68 77 0.36 109 P 3 TWD 22 F06 -1.40 TEH TEC 38 COLD 61OUL 100 79 0.80 122 P 3 TWD 32 F06 +0.91 TEH TEC 38 COLD 61OUL 103 78 0.32 109 P 3 TWD 21 CBC +1.80 TEH TEC 38 COLD 61OUL Total Tubes : 3 Total Records: 3 S G A Tubes Preventatively Plugged QUERY: QueryMl ROW LINE VOLTS DEC CHM IND %TW LOCATION EXT EXT CAL t LEG PROBE 68= ==== ====e= === === === ====8==L===1====== = =

68 77 PTP TEH TEC 38 COLD 61OUL 100 79 PTP TEH TEC 38 COLD 61OUL 103 78 PTP TEH TEC 38 COLD 610UL Total Tubes  : 3 Total Records: 3 S/G B Tubes with Bobbin 20-100% TWD Indications No damage was reported in S/G B that exceeded 20% wall thickness penetration.

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 1 Page 5 S/G A:

Tubes with Bobbin 1-19% TWD Indications QUERY: QueryMl ROW LINE VOLTS DEG CHN IND %TW LOCATION EXT EXT CAL t LEG PROBE

=

77 92 0.20 127 P 3 TWD 14 F09 -2.28 TEH TEC 20 COLD 610UL 79 92 0.15 130 P 3 TWO 11 F09 -1.99 TEH TEC 20 COLD 0.13 114 P 3 TWD 11 F06 +1.30 TEH TEC 38 COLD 610UL 84 99 93 0.14 124 P 3 TWO 11 F04 -0.61 TEH TEC 20 COLD 610UL 88 610UL 78 0.25 112 P 3 TOD 16 CBC +1.91 TEH TEC 20 COLD 91 92 77 0.13 127 P 3 TWD 11 CBC +0.37 TEH TEC 38 COLD 61OUL 95 92 0.19 107 P 3 TWD 13 F09 -1.93 TEH TEC 20 COLD 610UL 97 92 0.13 123 P 3 TWD 11 F09 -2.02 TEH TEC 38 COLD 610UL 144 0.11 155 P 3 TWD 10 OIC -1.53 TEH TEC 62 COLD 610UL 97 0.24 124 P 3 TWO 17 02C -1.56 TEH TEC 62 COLD 610UL 78 0.27 155 P 3 TWD 18 CBC +1.74 TEH TEC 38 COLD 610UL 99 0.14 111 P 3 TWO 11 F06 -1.07 TEU TEC 22 COLD 610UL 102 111 0.12 115 P 3 TWD 9 F09 -1.92 TEH TEC 20 COLD 610UL 103 92 0.25 109 P 3 TWD 17 F06 -0.99 TEH TEC 38 COLD 610UL 114 75 0.12 137 P 3 ThO 9 F10 +2.24 TEH TEC 20 COLD 610UL 115 78 115 82 0.19 130 P 3 rWD 15 F05 +0.89 TEH TEC 61 COLD 610UL 128 51 0.14 74 P 3 TWD 11 F10 +0.54 TEH TEC 41 COLD 61OUL Total Tubes  : 16 Total Indications: 17 S/G B:

Tubes with Bobbin 1-19% TWD Indications QUERY: QueryMl ROW LINE VOLTS DEG CHN IND %TW LOCATION EXT EXT CAL

• LEG PROBE 81 102 0.14 125 P 3 TWD 12 F04 -1.80 TER TEC 21 COLD 610UL 97 144 0.08 158 P 3 TWD 8 05H +1.46 TEH TEC 52 COLD 610UL 110 91 0.10 77 P 3 TWO 9 F06 -1.38 TEH TEC 36 COLD 610UL 114 51 0.08 156 P 3 TWO 6 F05 -1.42 TEH TEC 36 COLD 61OUL Total Tubes  : 4 Total RIndications: 4

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 2 Page 1 REQUEST FOR ADDITIONAL INFORMATION SLI-19 STEAM GENERATOR TUBE INSERVICE INSPECTION SPECIAL REPORT ST. LUCIE NUCLEAR PLANT, UNIT I DOCKET NUMBER 50-335 NRC Request 1:

St. Lucie Unit 1 Technical Specification (TS) 4.4.5.5.b requires the licensee to provide the location and percent of wall thickness penetration for each indication of an imperfection.

This technical specification also requires identification of tubes plugged. Please provide the location of the three tubes that were plugged in steam generator A (i.e., row, column, and axial location of the flaw). In addition provide the location and percent of wall thickness penetration for each indication of an imperfection in both steam generators.

FPL Response 1:

The required information is provided in the enclosed listings, which include indications 1-19%

through-wall for both steam generators, and indications 20% or greater through-wall for steam generator 1A (S/G 1B does not contain any indications 20% or greater). A listing for tubes preventatively plugged in steam generator 1A is also provided.

NRC Request 2:

Your report identifies the population of tubes that are experiencing wear at U-bend support structure locations. There are different types of wear mechanisms, which behave differently and may present challenges to tube integrity. To help the NRC staff in understanding the identified indications of wear, please discuss the extent to which these wear indications are considered "typical fan bar wear," "atypical U-bend wear," or "localized U-bend wear." Typical fan bar wear refers to wear caused by the thermal hydraulic conditions and tube-to-support clearances, which can vary because of manufacturing tolerances. Atypical U-bend wear refers to pit-like indications found at flat-bar supports and theorized to be the result of asperities on the flat bars introduced during fabrication. Localized U-bend wear refers to wear

'localized" to specific columns of tubes and possibly the adjacent column as a result of arch-bar distortion instead of a more random manufacturing tolerance issue (which causes typical fan bar wear).

Please discuss how the nature of the wear detected during this outage compares to the wear indications detected in 1999 (i.e., what was the cause of wear indications in 1999).

FPL Response 2:

Most indications are localized U-bend wear occurring at flat-bar supports in line 77-79 and line 92-93 in steam generator 1A, which account for 13 of 14 tubes plugged to date. One additional tube (S/G 1A, R27 L100) was plugged in 1999 for an atypical pit-like wear indication at a flat-bar support in the U-bend that is likely due to a manufacturing anomaly.

In the most recent inspection at SL1-19, 16 new wear indications were reported. Five of

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 2 Page 2 these were localized wear in the U-bend as discussed above, three of which were plugged (see listing "S/G A Tubes Preventatively Plugged"). Eleven of these are typical wear occurring randomly at flat-bar supports in the U-bend and straight tube regions. Wear indications remaining inservice at the present time include localized U-bend wear and typical (i.e., random) wear indications.

NRC Request 3:

In several Babcock and Wilcox replacement steam generators currently in service, tube-to-tube contact or tubes in close proximity have been observed. For St. Lucie Unit 1, please discuss how many tubes are currently considered to be in close proximity and whether any tube wear has been observed at the locations of close proximity. In addition, please discuss whether the number of tubes in close proximity has increased, decreased, or remained the same since the steam generators were installed. If the number of tubes in close proximity is increasing with time, please discuss the cause (the staff understands that the tube proximity issue is a result of manufacture and that it was expected that the condition may correct itself with time).

FPL Response 3:

The approximate number of tubes in close proximity reported during the three inservice inspections conducted to date (SL1-16, SL1-17 and SL1-19) are shown below. The number remains relatively constant over time and none of the tubes contained any wear degradation based on bobbin and rotating probe inspections completed.

Steam Generator Tubes In Close Proximity- St. Lucie Unit 1 SL1-16 SLI-17 SL1-19 S/G 1A 54 54 56 S/G 1B 45 52 48 NRC Request 4:

There is limited steam generator design information in the St. Lucie Updated Final Safety Analysis Report. In order for the staff to better understand the design of your steam generators and the location of the indications described in your reports, please provide the following design information for St. Lucie Unit 1: (a) the manufacturer's model number for the replacement steam generators, (b) tube manufacturer, (c) outer diameter and nominal wall thickness of tubes, (d) number of tubes in each steam generator, (e) tube pitch and pattern ( e.g., 0.95 inches triangular), (f) tubesheet thickness (with and without clad), (g) a sketch depicting the tube support structure naming (h)anti-vibration bar (fan bar) design, (i) tube support material (e.g., 410 Stainless Steel), 0) a sketch of a tubesheet map which depicts the rows and columns of the tubes in the steam generators, (k) smallest U-bend radius in the steam generator and the radii of the row 1 tubes, (I)stress relief after bending of tubes (e.g., stress relief of the entire tube length for the tubes in rows 1 through 27).

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 2 Page 3 FPL Response 4:

Babcock & Wilcox International does not use model numbers, but instead uses a descriptive title and serial number in the manufacture of their steam generators as shown in the table below. Additional figures are enclosed as identified in the table.

St. Lucie Unit I Steam Generator Design Information (a) the manufacturer's model number St. Lucie Nuclear Power Plant Unit 1 Replacement Steam Generator SIG A S/N 769802A, S/G B S/N 769801 B (b)tube manufacturer Sumitomo Special Metals (c) tube outer diameter & nominal wall 0.75 inches x 0.045 inches thickness (d) number of tubes in each steam 8523 generator (e) tube pitch and pattern ( e.g., 0.95 1.0 inch triangular inches triangular)

(f) tubesheet thickness (with/without clad) 21.875 inches /21.50 inches (g) a sketch depicting the tube support See Figure 1 structure naming (h) anti-vibration bar (fan bar) design, See Figure 2 (i) tube support material (e.g., 410 410 Stainless Steel Stainless Steel)

0) a sketch of a tubesheet map which See Figure 3 depicts the rows and columns of the tubes in the steam generators (k) smallest U-bend radius in the steam Row 3 has the smallest radius of 3.905 generator and the radii of the row 1 tubes inches, Row 1 radius measures 4.272 inches (I) stress relief after bending of tubes (e.g., The u-bend regions of tubes in Row 1-20 are stress relief of the entire tube length for stress relieved after bending the tubes in rows 1 through 27)

NRC Request 5:

Steam generator inspections may not be required each refueling outage to meet TS requirements. To ensure NRC staff records are accurate, please confirm that no tube inspections were performed during the fall 2002 refueling outage (SL1-1 8).

FPL Response 5:

No tube inspections were performed during the fall 2002 refueling outage (SL1 -18).

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 2 Page 4 FIGURE 1 PSL-1 Replacement Steam Generator Support Identification

St. Lucie Unit I Docket No. 50-335 L-2005-234 Attachment 2 Page 5 FIGURE 2 PSL-1 Replacement Steam Generator U-Bend Structure Identification

St. Lucie Unit 1 Docket No. 50-335 L-2005-234 Attachment 2 Page 6 Lines ROWS S

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