NL-15-0850, Refueling Outage 2R23 Steam Generator Tube Inspection Report

Refueling Outage 2R23 Steam Generator Tube Inspection Report

ML15131A333
Person / Time
Site:	Farley
Issue date:	05/11/2015
From:	Pierce C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-15-0850
Download: ML15131A333 (7)

Text

Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 Fax 205.992.7601 so MAY 1 1 2015 Docket Nos.: 50-364 NL-15-0850 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Refueling Outage 2R23 Steam Generator Tube Inspection Report Ladies and Gentlemen:

In accordance with the requirements of Joseph M. Farley Nuclear Plant Technical Specification 5.6.1 0, Southern Nuclear Operating Company submits the enclosed report of the steam generator tube inspections performed during the twenty-third refueling outage on Unit 2 (2R23.)

This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.

Sincerely, t.J<. ~

C.R. Pierce Regulatory Affairs Director CRP/JMC

Enclosure:

2R23 Steam Generator Tube Inspection Report

U.S. Nuclear Regulatory Commission NL-15-0850 Page2 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Ms. C. A. Gayheart, Vice President - Farley Mr. M.D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Ms. B. L. Taylor, Regulatory Affairs Manager- Farley RTYPE: CFA04.054 U. S. Nuclear Regulatorv Commission Mr. V. M. McCree, Regional Administrator Mr. S. A. Williams, NRR Project Manager- Farley Mr. P. K. Niebaum, Senior Resident Inspector- Farley

Joseph M. Farley Nuclear Plant- Unit 2 Refueling Outage 2R23 Steam Generator Tube Inspection Report Enclosure 2R23 Steam Generator Tube Inspection Report

Enclosure to NL-15-0850 JOSEPH M. FARLEY NUCLEAR PLANT- UNIT 2 2R23 STEAM GENERATOR TUBE INSPECTION REPORT The Joseph M. Farley Nuclear Plant (Farley) - Unit 2 Refueling Outage 23 (2R23) was conducted after cumulative Replacement Steam Generators (RSG) service equivalent to approximately 12.6 effective full power years (EFPY) while the service from previous RSG eddy current inspections at 2R21 was approximately 2.81 EFPY. No tube leakage was reported during this operating interval comprising of cycles 22 and 23. As of Farley 2R23, approximately 134.8 effective full power months (EFPM) of the 144 EFPM in the first sequential period were accrued. Farley 2R23 is the last inspection in this sequential period. Based on steam generator (SG) eddy current and visual inspection data, there are two existing degradation mechanisms in the Farley Unit 2 RSGs. Both degradation mechanisms were observed for the first time during the 2R23 inspection. The existing degradation mechanisms are:

• Mechanical Wear at Anti-Vibration Bar (AVB) Tube Supports

• Mechanical Wear at Tube Support Plate (TSP) Intersections A. The Scope of Inspections Performed on Each Steam Generator:

The inspection program, as required by EPRI PWR SG Examination Guidelines, addressed the potential degradation mechanisms for Farley Unit 2 RSGs. The defined scope for Farley Unit 2 implemented during refueling outage 2R23 included the following:

1. Bobbin exams (all 3 SGs)

• 50% Bobbin full length examination of tubes in all SGs not inspected at 2R21, 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).

2. +Point rotating pancake coil (RPC) (all 3 SGs)

• 50% +Point examination of Row 1 and Row 2 U-bends in all SGs not inspected at 2R21. The tubes in this sample population were tubes that are also tested as part of the bobbin program.

• +Point examination of the TIS periphery tubes consisting of every other tube three tubes deep on both the HL and CL side at the TTS +/-

3 inches in all SGs. The total number of tests represents at least a 20% +Point sample.

• 20% +Point examination of all dents and dings ~ 2 volts in all SGs. All additional dents and dings ~ 2 volts identified by the bobbin program were also examined.

'* +Point tests of Special Interest tube locations in both the HL and CL of possible flaw from the bobbin program to characterize underlying conditions. The presence of indications from previous inspections listed was taken into account in developing the Special Interest program.

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Enclosure to NL-15-0850

3. Visual inspection in all SGs of channel head primary side HL and CL in accordance with Westinghouse NSAL-12-1 inclusive of the entire divider plate to channel head weld and all visible clad surfaces.

4. Top of Tubesheet Foreign Object Search and Retrieval (FOSAR) (all 3 SGs)

• Visual examination of tube bundle periphery tubes from both the annulus and tubelane on both the HL and CL

• An in-bundle visual inspection with a focus on regions where objects have been previously identified

• Previous loose part locations

5. Steam Drum and Feedring inspection (all 3 SGs)

B. Active *Degradation Mechanisms Found:

Anti-Vibration Bar (AVB) Wear Two indications of A VB wear were identified in two different tubes in SG B during Farley 2R23. The bobbin probe sizing of the larger of the two indications was measured at 14% through-wall (TW) while the other was 10% TW. Based on the inspection data structural integrity requirements have been met at the 2R23 inspection. The complete listing of AVB wear indications is located in Table 1.

Tube Support Plate (TSPl Wear Four indications of mechanical wear at or near tube intersections with TSP were identified during 2R23. The bobbin inspection program performed identified four wear indications in three different tubes. There were three such wear indications in SG A and one in SG B. The indications were subsequently examined with the +Point probe for characterization. The +Point examination allowed the eddy current data analysts to confirm these bobbin calls as volumetric tube wear at TSP intersections.

Both bobbin and +Point are qualified for sizing of this degradation and the sizing results for each of these techniques is presented in Table 2 and Table 3. SG B Row 2 Column 60 (R2C60) was the only TSP wear intersection to have measurable tube wear. This tube was also the only location where the wear is observable over the entire 1.12 inch TSP intersection. SG B R2C60 tube was plugged due to tube support plate wear at TSP #5 on the cold leg side of the tube measured at 24% TW.

Due to uncertainty in the growth rate of the indication, the tube was plugged to support the planned eddy current inspection period.

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Enclosure to NL-15-0850 C. Nondestructive Examination Techniques Utilized for Each Degradation Mechanism Bobbin and +Point RPC eddy current probes were used to detect potential degradation mechanisms.

D. Location, Orientation (if linear) and Measured sizes (if available) of Service Induced Indication Table 1: Farley 2R23 AVB Wear Indications SG Row Column Indication %TWO Location B 36 60 PCT 14 AV3 B 41 44 PCT 10 AV4

% TWO- Percent Through-wall Depth PeT-Volumetric Indication Sizing AV#- Location of AVB intersection with the tube Table 2: Farley 2R23 TSP Wear Indications - +Point SG Row Column Indication %TWO Location B 2 60 PCT 24 5C B 2 60 PCT 4 5C A 4 20 PCT 16 5C A 4 20 PCT 5 6C A 41 60 PCT 10 7C Table 3: Farley 2R23 TSP Wear Indications - Bobbin SG Row Column Indication %TWO Location B 2 60 DSI 24 5C A 4 20 DSI 15 5C A 4 20 DSI Note 1 6C A 41 60 DSI 9 7C Note 1 : Th1s 1nd1cat1on had no measurable volumetnc depth by bobbin DSI - Distorted Support Indication E. Number of Tubes Plugged During the Inspection Outage One tube, Row 2 Column 60, was plugged in SG 28 during 2R23 refueling outage.

F. Total Number or Percentage of Tubes Plugged to Date One tube (row 2, column 60) was plugged in SG 28 during 2R23 refueling outage. No tubes have been plugged in SG 2A or SG 2C to date.

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Enclosure to NL-15-0850 Table 4: Farley Unit 2 SG Plugged Tubes SG Number of Tubes plugged Total tubes Percent tubes in 2R23 plugged plugged A 3592 0 0 0%

B 3592 1 1 0.03%

c 3592 0 0 0%

Total 1ons 1 1 0.01%

G. The results of Condition Monitoring, including the results of Tube Pulls and In-Situ Testing.

Based on the inspection data, AVB wear and TSP wear were the only active degradation mechanisms observed in 2R23. No indications of AVB and TSP wear were found to be in excess of the Condition monitoring limits. No tubes exhibited degradation that required in situ pressure testing and there was no primary to secondary leakage prior to the end of the inspection interval. No secondary side tube damage was attributed to the foreign objects identified from 2R23 top of tubesheet visual inspections and FOSAR. There were no structural anomalies observed in any of the RSGs during the Farley 2R23 steam drum inspection. The SG performance criteria for operating leakage and structural integrity were confirmed to have been satisfied for the preceding Farley Unit 2 RSG operating interval.

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