NRC-2013-0008, Submittal of Fall 2012 Steam Generator Tube Inspection Report

Submittal of Fall 2012 Steam Generator Tube Inspection Report

ML13140A015
Person / Time
Site:	Point Beach
Issue date:	05/16/2013
From:	Millen M Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-2013-0008
Download: ML13140A015 (8)

Text

NExTerao ENERGYv May 16, 2013 BEACH NRC 2013-0008 TS 5.6.8 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 2 Docket 50-301 Renewed License No. DPR-27 Fall 2012 Unit 2 (U2R32)

Steam Generator Tube Inspection Report Pursuant to the requirements of Point Beach Nuclear Plant (PBNP) Technical Specification (TS) 5.6.8, "Steam Generator Tube Inspection Report," NextEra Energy Point Beach, LLC is submitting the 180-day Steam Generator Tube Inspection Report. The enclosure to this letter provides the results of the fall 2012, Unit 2 (U2R32) steam generator tube in-service inspections.

This letter contains no new Regulatory Commitments and no revisions to existing Regulatory Commitments.

If you have questions or require additional information, please contact Mr. Andrew Watry at 920/755-7393.

Very truly yours, NextEra Energy Point Beach, LLC Mike Millen Licensing Manager Enclosure cc: Administrator, Region III, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW ho,¢ NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

ENCLOSURE I NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNIT 2 FALL 2012 UNIT 2 (U2R32)

STEAM GENERATOR TUBE INSPECTION REPORT 6 pages follow

1.0 Introduction Point Beach Nuclear Plant (PBNP) Unit 2 is a two loop Westinghouse-designed Pressurized Water Reactor (PWR) with Model D47F replacement steam generators (SGs). The original 44 Series SGs, which had mill annealed Ni-Cr-Fe Alloy 600 tubing, were replaced because of various types of tube degradation. The replacement SGs were installed in U2R22. They have been in service since August 1997 and have operated for 12.97 effective full power years (EFPY) by refueling outage U2R32.

The U2R32 inspection scope and plan were based on the Degradation Assessment prepared prior to U2R32 refueling outage. No crack-like indications were reported during the U2R32 SG eddy current inspection. The only damage mechanisms observed during the inspection were tube wear at anti-vibration bars (AVB) and at broached tube support plate (TSP) locations.

No new degradation due to maintenance related activities was detected. No new wear due to suspected foreign objects was identified. The secondary side inspection showed no significant degradation.

All of the AVB wear depths identified were below the condition monitoring limit defined in the U2R32 degradation assessment. Therefore, condition monitoring was satisfied for AVB wear in SG 2A. No AVB wear was detected in SG 2B.

The depths of the wear indications at TSP were below the condition monitoring limit defined in the degradation assessment. Therefore, condition monitoring was satisfied for tube wear at TSPs in SG 2A. No TSP wear was detected in SG 2B.

No primary-to-secondary leakage was reported during normal operation in the last three operating cycles. This satisfied the performance criterion for leakage integrity during normal operation.

In summary, all SG performance criteria were satisfied.

2.0 Scope of Inspections Performed 2.1 Inspection for Steam Generator A and Steam Generator B consisted of:

a. Bobbin Inspection - All Accessible Tubes:

100% bobbin full length examination of tubes, except for Rows 1 and 2 which were inspected from tube end to the top TSP from both the hot leg (HL) and cold leg (CL).

b. Motorized Rotating Pancake Coil (MRPC) Inspection +PointTM):

• 33% +PointTM examination of Row 1 and Row 2 U-bends.

• +PointTM examination of all peripheral tubes (2 tubes deep within the "no tube lane" and 3 tubes deep at the circumference) on the HL and CL top of tubesheet (TTS) (+/-3 inches) for loose part wear.

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20% (excluding peripheral tubes) +PointTM examination at the HL TTS from TSH +/-3 inches. This sample population was taken from tubes that were not +PointTM inspected at the HL TTS during U2R24, U2R26, or U2R29.

100% +PointTM examination of all dings > 5 volts in the HL and U-bend, including all new dings > 5 volts identified during U2R32.

+PointTM examination of PLP signals from U2R29.

c. Diagnostic and special interest (SI) inspections based on historical data and the results of the initial bobbin and MRPC inspections were performed to characterize and/or size any identified indications.

d. Installed tube plugs were visually inspected.

e. Visual inspection of the channel head bowl in both HL and CL as recommended in Nuclear Safety Advisory Letter 12-1 (NSAL-12-1).

2.2 Secondary Side The following secondary side work was performed in both SGs:

• Sludge Lancing

• FOSAR above the tubesheet

• Upper Steam Drum Inspection on the following components: feedring, J-tubes, backing ring, thermal sleeves, and primary separators.

3.0 Degradation Mechanisms Found The following degradation mechanisms were observed in the PBNP Unit 1 SGs during U2R32:

3.1. Tube Wear at Anti-Vibration Bar There were eight indications of wear at the AVBs in six tubes in SG 2A. There were no tubes in SG 2B with indications of wear at the AVBs.

3.2. Tube Wear at Tube Support Plates (TSP)

The distorted support indications (DSI) reported by bobbin inspections were subjected to +PointTM inspection. There were two bobbin DSI calls which were confirmed by +PointTM inspection to be flaws due to tube wear. They were both in SG 2A, in Tubes R12C53 and R1 5C64.

ii. The DSI indication in Tube R12C53 was at the broached TSP designated as 06H, with two separate flaws at land contact points. The results of the sizing showed 3% through-wall (TW) and 2% TW wear depths in R12C53.

iii. The DSI in R1 5C64 was at the 05H broached support plate. The results of the sizing showed 1% TW in R1 5C64.

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3.3. PLP (Possible Loose Part)

PLP signals were reported by the bobbin and top of the tubesheet +PointTM inspections. A +PointTM inspection was performed at all the PLP locations identified by bobbin. In addition to the identification of any PLPs, the +PointTM inspection also helped identify if any tube degradation had occurred due to the PLP. The PLP locations identified by +PointTM during U2R32 are shown below in Table 4-3. PLP signals are not a degradation mechanism.

4.0 Service Induced Flaws 4.1 Mechanical Wear Indications at Anti-vibration Bar (AVB) 4.1.1. Tube Wear at Anti-Vibration Bar There were eight indications of wear at the AVBs in six tubes in SG 2A.

There were no tubes in SG 2B with indications of wear at the AVBs.

During the U2R29 outage, AVB wear was reported at seven locations in SG 2A. During the current inspection, AVB wear was reported at all seven of the prior locations and at one new location in the same SG. The data is shown below in Table 4-1.

Table 4-1 Wear at AVB - SG 2A 2012 2008 2003 2000 1998 U2R32 U2R29 U2R26 U2R24 U2R23 Row Col Loc  % TW  % TW  % TW  % TW  % TW No 84 45 AV5 12 11 Insp. 8 NDD No 84 45 AV6 8 5 Insp. NDD NDD No 78 59 AV4 9 8 Insp. 6 NDD No 78 59 AV5 8 7 Insp. 6 NDD 79 62 AV3 12 8 10 NDD NDD 84 63 AV5 7 7 5 NDD NDD 79 66 AV5 9 6 6 NDD NDD No 82 69 AV1 8 7 Insp. NDD NDD NDD - No degradation detectable 4.2 Wear at Support Plates 4.2.1. During the U2R29 outage, TSP wear was reported at one TSP location in SG 2A with two wear scars at two of the three contact lands in the trefoil broach hole. During the current inspection, TSP wear was reported at the prior locations and at one new location in the same SG as shown in Table 4-2. No TSP wear has been reported in SG 2B.

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Table 4-2 Wear at TSP SG 2A 2012 2008 2003 2000 1998 ROW COL LOC U2R32 U2R29 U2R26 U2R24 U2R23

%TW %TW %TW %TW %TW 12 53 06H 3 7 No Insp. No size NDD 12 53 06H 2 4 No Insp. No size NDD 15 64 05H 1 NDD No Insp. No size NDD 4.3 Possible Loose Parts (PLP) 4.3.1. During the foreign object search and retrieval (FOSAR) operation, an attempt was made to find and verify PLP reported from the eddy current inspection. Two sludge rocks were observed at two PLP locations during FOSAR. The +PointTM inspection of the tubes with PLP and surrounding tubes showed no degradation in the tubes around the reported PLP locations.

Table 4-3 Possible Loose Parts Location - U2R32 SG Row Column Location Elevation A 32 7 TSC +1.52" B 3 40 TSH +0.10" 5.0 NDE Techniques for Damaqe Mechanisms The following is the list of EPRI technique sheets used for detection for the degradation modes that may be present during the steam generator inspection in U2R32.

AVB Wear 96004.1 Revision 13, (bobbin)(diff mode)

TSP/FDB Wear 96004.1 Revision 13, (bobbin; 96910.1 Revision 10 (+Point')

Mechanical Wear 27091.2 Revision 0 (bobbin),

27901.3 through 27907.3 Revision 1

(+PointTM)

Loose Part Wear 27091.2 Revision 0 (bobbin);

27901.3 through 27907.3 Revision 1

(+PointmM), 21998.1 Revision 4 (+PointTM)

Axial ODSCC at TTS and Expansion 128424 Revision 3, Transitions 128425 Revision 3, 128431 Revision 3, 128432 Revision 3 (+PointTM Circumferential ODSCC at Expansion 21410.1 Revision 6 (+PointT ")

transitions Page 4 of 6

Axial ODSCC at Ding/Dent, Freespan, and 128411 Revision 3, Supports 128413 Igevision 3 (bobbin),

128424 Revision 3, 128425 Revision 3, 128431 Revision 3, 128432 Revision 3 (+PointTm Circumferential ODSCC at Ding/Dent, 21410.1 Revision 6 (+Point"')

Freespan and Supports 6.0 Plugging Two tubes were plugged during U2R23 due to minor loose parts wear. Two tubes were plugged administratively during U2R24 due to excessive noise in the eddy current test data. No other tubes have been plugged in the PBNP Unit 2 SGs.

Table 6-1 Total Tubes Plugged and Plugging Percentage SG 2A SG 2B Total Tubes Plugged 0 4 Plugging Percentage 0.000% 0.114%

7.0 Condition Monitoring Assessment Results All of the AVB wear depths identified were below the condition monitoring limit. No AVB wear was detected in SG 2B. Therefore, condition monitoring was satisfied for AVB wear in SG 2A and 2B.

The depths of the wear indications at TSP were below the condition monitoring limit. No TSP wear was detected in SG 2B. Therefore, condition monitoring was satisfied for tube wear at TSPs in SG 2A and 2B.

No tube wear due to loose parts was reported during U2R32. Hence, condition monitoring was satisfied for this degradation mechanism in both SGs.

No primary-to-secondary leakage was reported during normal operation in the last three operating cycles. This satisfied the performance criterion for leakage integrity during normal operation.

In summary, all SG performance criteria were satisfied for the current outage.

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8.0 Secondarv Side InsDections/Cleanincl Secondary side sludge lancing and FOSAR above the tubesheet were performed in each SG during U2R32. In addition, a steam drum inspection was performed by manual entry into the SG through the secondary side manway. The upper steam drum along with the feedring, J-tubes, backing ring, thermal sleeves, and primary separators were visually inspected in both SGs and no anomalies were noted.

No anomalous conditions adverse to structural integrity were reported from the above inspections. The FOSAR operation was performed in the annulus and tube lane in both SGs. One foreign object (judged to be a piece of flexitallic gasket) was retrieved from the annulus region of SG 2A. The PLP indications, by eddy current testing, reported slightly above the top of the tubesheet location were subjected to FOSAR as access allowed. Sludge rocks were identified at the two PLP locations. The sludge rocks are benign to tubing and were not removed.

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