CP-201900378, Transmittal of Seventeenth Refueling Outage (2RF17) Steam Generator 180 Day Report

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Transmittal of Seventeenth Refueling Outage (2RF17) Steam Generator 180 Day Report
ML19171A190
Person / Time
Site: Comanche Peak Luminant icon.png
Issue date: 06/10/2019
From: Hicks J
Luminant, TXU Energy, Vistra Energy
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-201900378, TXX-19063
Download: ML19171A190 (19)
v • d • e


Text

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  • energy I m Luminant Jack C. Hicks Manager, Regulatory Affairs Luminant P.O. Box 1002 6322 North FM 56 Glen Rose, TX 76043 o 254.897.6725 CP-201900378 TXX-19063 ATIN: Document Control Desk Ref 10 CFR 50.55a U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 6/10/2019

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-446 UNIT 2 SEVENTEENTH REFUELING OUTAGE (2RF17) STEAM GENERATOR 180 DAY REPORT

Dear Sir or Madam:

By means of the enclosure with this letter, Vistra Operations Company LLC (Vistra OpCo) submits the Comanche Peak Nuclear Power Plant (CPNPP) Unit 2 steam generator tube inspection report for 2RF17 as required by Technical Specification 5.6.9. This communication contains no new licensing basis commitments regarding Comanche Peak Unit 2. If you have any questions regarding this submittal, please contact Jim Barnette at (254) 897-5866 or James.barnette@luminant.com. Sincerely, Enclosure - Comanche Peak Nuclear Power Plant 2RF17 Steam Generator 180 Day Report 6555 SIERRA DRIVE IRVING, TEXAS 75039 0214-812-4600 VISTRAEN ERGY.COM

TXX-19063 Page 2 of 2 c - Scott A. Morris, Region IV Natreon Jordan, NRR Resident Inspectors, Comanche Peak

Enclosure with TXX-19063 Comanche Peak Nuclear Power Plant 2RF17 Steam Generator 180 Day Report CPNPP This report is being submitted pursuant to TS 5.6.9, "Steam Generator Tube Inspection Report," to provide the results of the most recent CPNPP Unit 2 Steam Generator inservice inspection. Report Cover Page

Enclosure with TXX-19063 Steam Generator Configuration The Comanche Peak Nuclear Power Plant (CPNPP) Unit 2 Nuclear Steam Supply System (NSSS) has four Westinghouse Model D5 Steam Generators (SG) each with 4570 thermally treated Alloy 600 U-tubes. Each U-tube has a nominal outside diameter (OD) of 0.750 inch, a nominal tube wall thickness of 0.043 inch, and a straight length ranging from 303.73 inches (Row 1) to 305.49 inches (Row 49), based on the tube schedule drawing. The tubesheet is 21.23 inches thick with a full depth hydraulic expansion of the tubes in both the hot leg (HL) and the cold leg (CL). Approximately one inch of the tube at both ends was tack expanded prior to tube-end welding. On the hot leg side, the U-tubes are supported by seven (7) tube support plates (TSPs). A flow distribution baffle (FOB) plate located between the tubesheet and the first TSP helps distribute the secondary side flow over the tubesheet. On the cold leg side there are four (4) TSPs, six (6) preheater baffle plates and the FOB. The FOB and the lowest five preheater baffle plates are 0.75-inch-thick whereas the TSPs and the top preheater baffle plate are 1.12 inches thick. The FOB and the preheater baffle plates have round drilled holes whereas the TSPs have concave quatrefoil holes. All plates are made of Type 405 stainless steel. In the U-bend, the tubes are supported by two (2) sets of chrome-plated lnconel anti-vibration bars (AVBs). Figure 1 shows schematic of the Model D5 SG and Figure 2 shows the general location of the tube support plates and the baffle plates and the terminology used in the eddy current inspection designated plates. To reduce tube vibration, 140 tubes in each SG were hydraulically expanded at the B and D preheater baffle plates. This field modification was performed before the initial startup of CPNPP Unit 2. 1 of 16

Enclosure with TXX-19063 Figure 1 Unit 2 Model D5 Steam Generator General Arrangement t 63.84 4.03 814.56 1 129.00 812.03 3.02 l 129.00 17.06 Model os Owg.No.1103J99 2 of 16

Enclosure with TXX-19063 Figure 2 Unit 2 Model D5 SG General Location and Designation of Tube Support/Baffle Plates (Designa tions in parentheses show eddy current test terminology) 

                                               ----,I"I. . . ________

Access Port #2 --+ P (H11) ! C11 r N (H1D) C10 Located on the Y Axis MWY sideSG 2 &4 NZL side SG 1 & 3 M (H9) C9 l Access Port #1 --+ L (HS) cs J (H7) K (C7) Hand Hole "E" Located approximately H (C6) 4.3 Deg from 'Y' Axis on CL side F (H5) (:~ (C5) 1-------{ E (C4l C (H3) D (C3) Hand Hole "D" Located approximately Hand Holes 7 inches above BP 'B' "A", "B", and "C" Located at 9 at° B (C2) *z* on Axis Axes 'W', "X", and "Y" R *velfl. (H1) c1 1---- +---- -1._ 4 Inspection Ports at 90° atTTS Located approximately 5 inches above BP 'A' 3 of 16

Enclosure with TXX-19063 Inspection Summary The primary side inspection of the Comanche Peak Nuclear Power Plant (CPNPP) Unit 2 steam generators (SGs) consisted of base scope eddy current testing of 50% of the hot leg top of tubesheet region in SGs 2-01, 2-02, and 2-04 and a 100% sample in SG 2-03 during the Cycle 17 refueling outage (2RF17). This scope was in compliance with the Plant Technical Specification inspection requirement subsequent to the discovery of circumferential primary water stress corrosion cracking (PWSCC) tube flaws during the prior 2RF16 SG inspection. No other base scope inspections were required to be performed during the 2RF17 SG inspection to support tube integrity assessments for the next operating interval until 2RF18. A small number of special interest eddy current examinations using the +POINT' probe were performed to support tube integrity assessments for selected locations where a foreign object remains in the SG and locations where historical possible loose part (PLP) eddy current signals were reported in prior inspections. Permanent alternate repair criteria (H*) eliminated the need for inspecting tube sections from 14.01 inches below the top of the tubesheet to the tube end during the hot leg tubesheet inspection program. Sludge lancing and foreign object search and retrieval (FOSAR) activities were not performed during 2RF17. The base scope inspection program was completed as planned. No indications of PWSCC or other types of degradation were reported from the hot leg top of tubesheet inspection program. No unexpected results or significant findings emerged from the small special interest +POINT probe inspection program. The only degradation mechanism reported during the 2RF17 inspections was low level foreign object wear. All inspections were performed in accordance with the requirements of both the Electric Power Research Institute (EPRI) Steam Generator Integrity Assessment Guidelines

  • and the EPRI Steam Generator Examination Guidelines.

No tubes were plugged as a result of the base scope and special interest inspections. The following list is the current form of existing degradation mechanisms through 2RF17:

  • Tube wear at anti-vibration bars (AVBs)
  • Tube wear at preheater baffle plates (PHBs)
  • Tube wear at quatrefoil tube support plates (TSPs)
  • Tube wear due to foreign objects
  • Circumferential PWSCC at BLG/OXP locations with the hot leg (HL) tubesheet
  • Circumferential PWSCC at HL Tubesheet Expansion Transition Structural and leakage performance criteria were satisfied based on the inspection results. Hence, the CM requirements are satisfied. There was no primary-to-secondary operating leakage during the preceding inspection interval. An operational assessment of the current inspection results shows that the structural and leakage integrity will be satisfied for the next cycle and that it is acceptable to continue operation until the next planned inspection in spring 2020 (2RF18) for degradation mechanisms detected 4 of 16

Enclosure with TXX-19063 during 2RF17 and for existing degradation mechanisms previously detected at CPNPP Unit 2. Section 1 of this report describes the scope of inspections performed, including the nondestructive examination techniques utilized for each degradation mechanism and the scope expansion. Section 2 contains the inspection results, which include:

a. Degradation mechanisms found,
b. Number of tubes plugged during the inspection outage for each degradation mechanism,
c. Number and percentage of tubes plugged to date,
d. The results of condition monitoring, including the results of tube pulls and in-situ testing,
e. The primary to secondary leakage rate observed,
f. The results of monitoring for slippage.

Section 3 contains the location, orientation (if linear), and measured sizes (if available) of service induced indications. Section 1: Scope and Examination Techniques of Inspections Performed The actual inspections performed during 2RF17 met or exceeded both the Technical Specification minimum requirements and the requirements of the Electric Power Research Institute (EPRI) Pressurized Water Reactor (PWR) Steam Generator Examination Guidelines. The following primary side inspections were performed in all four SGs (unless specified):

  • 50% +POINT probe inspection of HL TTS +3.0 inches to -14.01 inches (H*

distance) in Steam Generators 1, 2 and 4.

  • 100% +POINT probe inspection of HL TTS +3.0 inches to -14.01 inches (H*

distance) in Steam Generator 3. 

  *    +POINT probe one tube "box-in" inspection of 2RF16 loose parts/wear indications with one cycle OA
  • 100% primary side visual inspection of all previously installed plugs in the HL and CL.
  • 100% primary side visual inspection of mechanical plugs installed at tie-rod locations (hot leg and cold leg) in each SG.
  • Primary side visual inspection in SG 2-01 of 11 solid bar A600 plugs installed in the no tube lane
  • Visual scan of the entire channel head bowl including all visible clad surfaces in the HL and CL.

No base scope expansion was required during the 2RF17 inspection. A small number of special interest +POINT probe inspections were performed per the inspection plan to investigate selected possible loose part (PLP) signals in the form of one tube "box-ins" in all directions of a reported PLP. 5 of 16

Enclosure with TXX-19063 Table 1 Nondestructive Examination Techniques Utilized for Each Degradation Mechanism Dcgnuhttion Detection Detection Sizing Location Sizing Technique ETSS l\"lechauism Probe Type Technique ETSS Probe Type Existing Degradation Mechanisms (2RFI 7) BLG/OXP in HL TI'S Circumferential 111524Rev.O-C +POINT 20510.1 Rev. 7 - C HL TfS Expansion +POINT PWSCC Transitions 

                                                                                                +POINT         21998.1 Rev. 4 (Note 1)

Foreign Objects +POINT 96910.1 Rev. 11 (Note 1) Wear (Object is Present or +POINT 21998.1 Rev. 4 Pancake 96911.1 Rev. 9 (Note 1) not Present) +POINT/Pancake 2790X Series for FO W car Potential DC!!radalion Mechanisms (2RF17) 128431 Rev. 3 - A 128424 Rev. 4 -A 128432 Rev. 2 - A Axial and Circ. +POINT HLTTS +POINT 128425 Rev. 4 -A ODSCC +POINT TR-107197 (Reference 15)- C 21410.1 Rev. 6 - C 21410.l Rev. 6- C (Note 2) BLG/OXP in HL TIS Axial +POINT 20511.1 Rev. 8-A +POINT 20511.1 Rev. 8 -A HL Expansion PWSCC Transitions Exislin!!. De2radalion Mechanisms (non-2RF17) 96004.3 Rev. 13 96004.3 Rev. 13 Wear AVBs Bobbin Bobbin 196041.1 Rev. 5 Bobbin 96004.3 Rev. 13 Bobbin 96004.3 Rev. 13 Wear TSPs, PBPs, & FDB +POINT 96910.1 Rev. 11 

                                                    +POINT               96910.1 Rev. 11 Pancake            96911.1 Rev.9
                                                                                                +POINT             21998.1 Rev. 411 J Wear            Foreign Objects        Bobbin               27091.2 Rev. 2        +POINT            96910.1 Rev. 11< 1)

Pancake 96911.1 Rev. 9(I) Potential D~radation Mechanisms (non-2RFI 7) 128411 Rev. 4 Bobbin 128413 Rev. 5 +POINT I2843 l Rev. 3 Axia!ODSCC TSP I28424 Rev. 4 +POINT I28432 Rev. 2 

                                                    +POINT 128425 Rev. 4 10013.1 Rev. 1 24013.1 Rev. 2 Bobbin                128413 Rev. 5        +POINT               128431 Rev. 3 AxialODSCC              Dings/Dents         +J>OINT                128424 Rev. 4        +POINT               128432 Rev. 2 128425 Rev. 4 22401.1 Rev. 4 21410.1 Rev. 6 Circ. ODSCC            Dings/Dents          +POINT               21410.1 Rev. 6         +POINT Note 5 6 of 16

Enclosure with TXX-19063 Degradation Detection Detection Sizing Location Sizing Technique ETSS l\'lcclmnism Probe Type Technique F.TSS Probe Tvpe 10013.1 Rev. 1 24013.1 Rev. 2 Bobbin 128413 Rev. 5 +POINT 128431 Rev. 3 Axial ODSCC Dings/Dents 128432 Rev. 2 

                                                          +POINT                128424 Rev. 4           +POINT 128425 Rev. 4 22401.1 Rev. 4 128431 Rev. 3 -A (OD) 128424 Rev. 4 -A (OD)                    128432 Rev. 2 -A (OD)

Tube Ex-panded 21410.1 Rev. 6 - C (OD) +POINT 21410.l Rev. 6 - C (OD) ODSCCiPWSCC +POINT (Note 2) atPBP 20511.1 Rev. 8-A(ID) +POINT 111524 Rev. 0 - C (ID) 20511.1 Rev. 8 -A (TD) 20510.1 Rev. 7 - C (TD) Axial and Circ. Row 1 &Row2 96511.2 Rev. 16 - A +POINT 20511.1 Rev. 8 - A 

                                                           +POINT PWSCC                   U-bends                               111524 Rev. 0- C           +POINT       20510.1 Rev. 7 - C Pitting, Volumetric       Top ofTubesheet,          Bobbin             96005.2 Rev. 9                          21998.1 Rev 4
                                                                                                        +POINT Indications               Freespan            +PO.INT             21998.1 Rev. 4 Non-Rele,*ant Mechanisms Diagnostic Ins1lection Axial and Circ.                                                   20511.1 Rev. 8 -A           +POINT       20511.1 Rev. 8-A HL Dents            +POINT PWSCC                                                         111524 Rev. 0 - C          +POINT       20510.1 Rev. 7 - C Notes:

(1) Technique selection is based on tlaw morphology (2) Sizing tmce11ainties are based on TR-107197 (Reference 16) 7 of 16

Enclosure with TXX-19063 Section 2: Inspection Results

a. Degradation Mechanisms Found Wear due to foreign objects was the only existing degradation mechanism reported during 2RF17. Circumferential Primary Water Stress Corrosion Cracking (PWSCC) within the tubesheet and at the expansion transitions was not observed in 2RF17.

Tube Wear Due to Foreign Objects Wear from foreign objects were reported during 2RF16. as shown in Table 2. For all wear indications listed in this table, no objects remain adjacent to the wear indications that remain in service. All of these historical indications were inspected using +POINT probes during 2RF16 and no change in the wear indications were reported, other than from normal eddy current sizing uncertainty. Tube R13C92 contained a 14% TW indication at the top edge of TSP C6 as reported during the prior 2RF16 inspection believed to have been caused by a foreign object; however, a foreign object was not evident from eddy current testing at this location. This indication was measured at 7% TW from re-analysis of the 2RF14 data. Three nearby tubes, but not adjacent tubes, (R12C90, R14C90 and R12C94) contained PLP signals during 2RF16 with no tube wear detected. An evaluation was completed in Westinghouse Letter WPT-18036, Revision 1, "Comanche Peak Nuclear Power Plant Unit 2, Evaluation of Steam Generator Secondary Side Foreign Objects at Comanche Peak Unit 2 during Spring 2017 Outage 2RF16," April 2017, for this indication to support acceptable operation for the time period from 2RF16 to 2RF17. Therefore, the 2RF17 inspection for foreign object wear included re-inspection of these four tubes and surrounding tubes with the +POINT probe. Additional locations of tubes near foreign objects remaining in the SGs and other tubes with 2RF16 PLP signals were also inspected during 2RF17 as listed in Tables 3 and 4. Also newly reported in 2RF16 was a 12% TW indication at the top edge of TSP C2 in Tube 21 C50 in SG 2-03. No foreign objects were reported at this location from visual inspections; however, a wire was reported by visual inspection near Tube R24C50. Review of historical eddy current data showed little to no change since 2RF14. Two foreign object wear indications were reported during the 2RF17 inspections. Tube R13C92 in SG 2-04 contained a 17% TW indication that measured 0.32 inch in axial extent located at TSP C6+0.42 inch. The flaw was sized with the pancake coil technique Examination Technique Specification Sheet (ETSS) 96911.1 as the flaw had little to no response from the +POINT probe coil. This flaw is historical in nature and had been reported during 2RF14 and 2RF16, measuring 7% TW and 14% TW, respectively. As part of the special interest one tube box-in of adjacent tubes for foreign object wear in Tube R13C92 (discussed above), Tube R12C91 in SG 2-04 was reported to contain a 6% TW indication that measured an axial length of 0.21 inch. The indication was located at TSP C6+0.5 inch. The flaw was sized with the pancake coil technique ETSS 96911.1 as the flaw had little to no response from the +POINT probe coil. This was the first report of a flaw with a measured depth at this location, 8 of 16

Enclosure with TXX-19063 however, the bobbin coil reported a historical distorted signal in each inspection since 2RF08 (2005). Review of historical eddy current data showed that a similar signal from the pancake coil was present at this location during 2RF16 with little to no change in depth (6% TW). Historical review of the 2RF08 and 2RF04 (1999) pancake coil data also showed a precursor signal with little change in character. The largest wear from foreign objects measured during 2RF17 was 17% TW with an axial extent of 0.32 inch (Tube R13C92 in SG 2-04) using the ETSS 96911.1 technique. This is less than the 49.4% TW CM structural integrity limit for a flaw with an axial length of 0.5 inch using the ETSS 96911.1 pancake coil sizing technique. For volumetric wear flaws with press-loading only condition, tube burst and ligament tearing (i.e., pop-through) are coincident, therefore, satisfaction of the tube burst criteria at 3b.PNOP also satisfies the accident induced leakage performance criteria (AILPC) at steam line break (SLB) conditions. For the remaining foreign object wear indications listed in Table 2 that were not inspected during 2RF17, no foreign objects remain adjacent to the affected tube locations, thereby removing the condition for continued wear progression. The largest of these flaw indications left in service during the prior 2RF16 inspection was 28% TW. This is less than the 55.8% TW CM structural integrity limit for a flaw with an axial length of 0.5 inch using the ETSS 21998.1 +POINT probe sizing technique. For volumetric wear flaws with pressure-only loading condition, tube burst and ligament tearing (i.e., pop-through) are coincident, therefore, satisfaction of the tube burst criteria at 3b.PNO also satisfies the AILPC at SLB differential pressure. Therefore, the SG structural and leakage performance criteria are satisfied for foreign object wear. Circumferential PWSCC within Tubesheet and at Expansion Transitions Circumferential PWSCC was first detected at CPNPP Unit 2 during 2RF16. Four indications of circumferential PWSCC were found in three tubes during the 2RF16 inspection. Three indications were found within the hot leg tubesheet below the top of tubesheet at identified BLG/OXP locations. One (1) indication was found within the top of the hot leg tubesheet expansion transition. All of the indications were located within SG 2-03. Table 5 provides the location and sizing information related to each flaw detected during the prior 2RF16 inspection. As a result of the 2RF16 inspection findings for circumferential PWSCC at hot leg tubesheet locations, inspections for this degradation mechanism were required to be performed during 2RF17. No indications of circumferential PWSCC were reported during the 2RF17 inspections. Since no indications of circumferential indications were reported during 2RF17, CM for this degradation mechanism is not required. 9 of 16

Enclosure with TXX-19063 Table 2 Summary of Foreign Object Wear Indications Reported in 2RF16 and 2RF17 2RF14 2RF16 2RF17 SG OUTAGE Row Col Volts Ind Locn Inch! Depth Depth Depth CrLen CrWid {%TW) (0/oTW) (%TW) 2-01<1> 2RF16(l) 4g(I) 33(!) 0.3 PCT C2 0 4 6 - - - 2-02 2RF16 3 114 0.26 PCT C4 0.4 24 24 - 0.21 0.44 2-02 2RF16 4 114 0.17 PCT C4 0.42 17 17 - 0.17 0.46 2-02 2RF16 6 1 0.17 PCT Cl 0.51 17 17 - 0.18 0.41 2-02 2RF16 6 2 0.33 PCT Cl 0.49 28 28 - 0.21 0.44 2-02 2RF16 6 2 0.16 PCT Cl 0.87 16 16 - 0.21 0.40 2-03 2RF16 21 50 0.11 PCT C2 0.66 -- 12 - 0.18 0.37 2-04 2RF17 12 91 0.09 PCT C6 0.50 -- --3 62 0.21 0.46 2-04 2RF17 13 92 0.40 PCT C6 0.42 72 142 172 0.32 0.56 2-04 2RF16 26 69 0.17 PCT C2 1.29 19 18 - 0.33 0.42 2-04 2RF16 32 71 0.27 PCT C2 0.64 25 25 - 0.22 0.38 2-04 2RF16 34 i7 0.15 PCT C2 0.53 16 17 - 0.29 0.40 {1) This was erroneously listed as foreign object wear in 2RF14 and 2RF16 tube integrity reports. This indication is a PBP wear indication and historically has been coll'ectly sized as a PBP wear indication. (2) Depth sizing of indication is based on ETSS 96511.1. (3) No degradation was reported during 2RF16. Historical data review in 2RF17 showed a precursor signal present at 2RF16 with little to no change, Table 3 Historical Foreign Objects Remaining in SGs Requiring Eddy Current Testing in 2RF17 2RF16 Item 2RF17 No. Length Width Height Inspection (Ref. 8) SG Lee: Row<1> Co1<2> Elev Description (inch) (inch) (inch) Result 1001 1 HL 38-39 95-99 Hll Wire 3 0.125 0.125 NDD

7. 8 2 PLPs: R7C3, 1 HL TTS Metal Strip 3 0.125 0.125 1010 8 3 R8C2, R8C3 2010 2 CL 29 39 C2 Flat Object 0.4 0.01 0.35 NDD 1'1etal PLPs: R42C64, 4 HL 47 64 TTS 2 0.312 0.5 4001 Remnant R43C64, R44C65 4010 4 CL 25,26 17 C2 Metal Shim 0.5 0.02 0.5 NDD Wear 17%TW 4 CL 13 92 C6 - -- --
        --                                                         Indication
1) +POINT probe target tube and one tube box-in of target tube(s).

10 of 16

Enclosure with TXX-19063 Table 4 Historical PLP Signals Requiring Eddy Current Testing in 2RF17 2RF17 Inspection Historical Insnection Result Result SG Row Col Volts Ind Locn Inchl Comment Ind. Volts 1 8 2 6.68 PLP HTS 0.50 2RF16 Item 1010 PLP 1.22 1 8 3 9.8 PLP HTS 0.29 2RF16 Item 1010 PLP 1.92 1 7 3 3.42 PLP HTS 0.07 2RF14 PLP PLPC 1) 0.69 3 5 30 4.29 PLP C6 0.39 2RF16 PLP PLP 4.34 3 5 31 3.01 PLP C6 0.50 2RF08 PLP PLPC1) 2.68 4 2 48 4.61 PLP C2 0.98 2RF16 PLP PLP 1.01 4 42 64 7.35 PLP HTS 0.55 2RF16 Item 4001 PLP 1.24 4 43 64 7.68 PLP HTS 0.34 2RF16 Item 4001 PLP 1.24 4 44 65 6.35 PLP HTS 0.07 2RF16 Item 4001 PLP 8.33 4 40 84 5.1 PLP HTS 0.17 2RF16 PLP NDD -- 4 12 90 3.28 PLP C6 0.42 2RF16 New PLP NDD -- 4 14 90 3.28 PLP C6 0.49 2RF16 New PLP NDD -- 4 12 94 6.7 PLP C6 0.48 2RF16 New PLP NDD -- 4 15 103 5.41 PLP C6 0.47 2RF16 New PLP PLP 4.1 (1) Result of one-nibe box-in \Vith +POINT probe Table 5 Summary of Historical Circumferential PWSCC Axial Circ. Circ. lnchl Depth Extent Extent Extent PDA SG Row Col Incl. Volts Location (in) (o/oTW) (in) (in) (cleg) (%) 2RF16 Inspection Results 2-03 5 79 SCI 0.71 TSH -1.11 48 0.29 0.20 31 4.1 2-03 48 86 SCI 0.55 TSH 0 69 0.22 0.39 60 11.5 SCI 0.92 TSH -2.03 46 0.26 0.21 32 4.1 2-03 1 94 SCI 0.80 TSH -2.02 43 0.22 0.23 35 4.2 2RF17 Inspection Results No circumfere11tial PWSCC indkations reported during 2RF17. 11 of 16

Enclosure with TXX-19063

b. Identification of Tubes Plugged No Tubes required plugging during 2RF17. Table 6 provides a history of tubes plugged in the Unit 2 SGs.
c. Total Number and Percentage of Tubes Plugged to Date The cumulative total number of tubes plugged in all SGs is 96, which is equal to 0.53% of the total number of tubes. Table 6 below lists the Unit 2 SG tube plugging information.

Table 6 Summary of All Plugged Tubes through 2 RF17 SG SG SG SG Outage Date EFPY Total Percent 2-01 2-02 2-03 2-04 Pre- Pre-0.000 5 3 3 9 20 0.11% Service Service 2RF01 Nov-94 0.910 0 0 0 0 0 0.00% 2RF02 Mar-96 2.090 0 0 0 0 0 0.00% 2RF03 Nov-97 3.489 3 5 0 0 8 0.04% 2RF04 Apr-99 4.706 1 0 0 4 5 0.03% 2RF05 Oct-00 6.137 3 0 0 1 4 0.02% 2RF06 Apr-02 7.519 0 4 7 0 11 0.06% 2RF07 Oct-03 8.825 3 0 0 1 4 0.02% 2RF08 Apr-05 10.203 5 2 4 2 13 0.07% 2RF09 Oct-06 11.637 No SG fuspection 0 0.00% 2RFI0 Apr-08 13.044 1 7 3 2 13 0.07% 2RF11 Oct-09 14.502 No SG fuspection 0 0.00% 2RF12 Apr-11 15.910 0 2 1 0 3 0.02% 2RF13 Oct-12 17.329 No SG fuspection 0 0.00% 2RF14 Apr-14 18.709 2 10 0 0 12 0.07% 2RF15 Oct-15 20.139 No SG hlspection 0 0.00% 2RF16 Apr-17 21.517 0 0 3 0 3 0.02% 2RF17 Dec-18 22.862 0 0 0 0 0 0.02% Tota1<1> 23 33 21 19 96 0.53% Percent 0.50% 0.72% 0.46% 0.42% 0.53% (1) There are 8 additional non-tube locations per SG (tie-rod locations) that contain shop plugs installed on the hot and cold leg side. These aire not included in the plugged tube percentages shown above, but may be included in the total number of tube plugs displayed in other lists and/or databases 12 of 16

Enclosure with TXX-19063

d. Results of Condition Monitoring (CM), Including the Results of Tube Pulls and In-Situ Testing The EPRI Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines requires the Condition Monitoring (CM) results from the current inspection be compared to the Operational Assessment (OA) from the previous inspection. This comparison identifies whether the underlying assumptions, input parameters, or methodology for performing OAs are conservative or require alteration prior to performing the next OA. Failure to meet CM requirements means that the projections of the prior OA were not conservative and that necessary corrective actions are to be identified. Even when CM requirements are met, this comparative review may identify adjustments to the OA inputs or assumptions.

For existing degradation mechanisms, a comparison of the previous OA projection was compared to the 2RF16 inspection results. The following provides a discussion of each comparison. Anti-Vibration Bars Wear Inspections for AVB wear were not required to be performed in 2RF17; thus, no inspections were performed and no AVB wear indications were reported during 2RF17. Therefore, comparison of the 2RF17 result to the prior 2RF16 OA cannot be performed. CM to prior OA comparisons performed in prior outages have resulted in conservative OA methods. Preheater Baffle Plates (PHB) / Tube Support Plates (TSP) Wear Inspections for PHB/TSP support wear were not required to be performed in 2RF17; thus, no inspections were performed and no support wear indications were reported during 2RF17. Therefore, comparison of the 2RF17 result to the prior 2RF16 OA cannot be performed. CM to prior OA comparisons performed in prior outages have resulted in conservative OA methods. Foreign Object Wear 2RF17 inspections for foreign object wear were limited to tubes and adjacent tubes with historical foreign objects that are remaining in the SGs where a one-cycle OA had been performed in 2RF16. Tubes and adjacent tubes of select historical PLP signal reported during 2RF16 were also inspected during 2RF17. No evidence of degradation was reported in these 2RF17 inspections. Additional inspections were performed in 2RF17 of a historical foreign object wear indication in Tube R 13C92 at TSP C6 in SG 2-04; adjacent tubes were also inspected. The 2RF16 foreign object evaluation projected that the flaw in this tube would progress from 14% TW in 2RF16 to 21% TW in 2RF17. The actual flaw depth as measured in 2RF17 was 17% TW. Therefore, the OA flaw projection methodology remains valid and conservative. 13 of16 J

Enclosure with TXX-19063 Channel Head Indications A channel head cladding anomaly has been reported within SG 2-01 and within SG 2-02. The cladding anomaly contained in the cold leg of SG 2-01 was previously estimated to be approximately 5/8-inch in length and half as wide . Evidence of this cladding anomaly has been present as early as 2003 , as referenced in the evaluation documented in Westinghouse Letter WPT-17797 , Revision 0, "Comanche Peak Nuclear Power Plant Unit 2 Steam Generator 1 Channel Head Cladding Flaw," April 2014. It is evident through comparison of the images shown in Figure 3 that there has been no apparent change in the anomaly character from 2RF14 through 2RF17 . Therefore , the conclusion of the engineering evaluation remains valid and applicable to the condition found in 2RF17. The evaluation concluded that there is significant margin between the estimated flaw depth and the American Society of Mechanical Engineers (ASME) Code allowable and no repairs are recommended . Figure 4 provides the 2RF17 and 2RF16 visual inspection images of the tubesheet cladding anomaly near Tube R1C109 in SG 2-02 hot leg. This shows a small "pit-like" anomaly that is approximately 1/16-inch in diameter. Comparison of the 2RF16 and 2RF17 visual inspection results shows no apparent change in the character of the anomaly. Figure 3 SG 2-01 Cold Leg Channel Head Cladding Anomaly Historical Inspection Result Figure 4 SG 2-02 Cold Leg Channel Head Cladding Anomaly Historical Inspection Results 14 of 16

Enclosure with TXX-19063 Secondary Side Integrity There was no sludge lancing, FOSAR, or upper tube bundle inspection activities performed during 2RF17. There were no anomalies or degradation of secondary side components reported in prior SG inspections. Upper steam drum visual inspections were performed in all four SGs during 2RF17. Components inspected included all accessible steam drum components such as primary and secondary moisture separator components, drains, steam vents, deck plates, support gussets, shell, and auxiliary nozzle. The steam drum inspections did not find any indications of rapidly progressing erosion, cracking, material loss or other forms of degradation. Small amounts of incipient erosion have been observed in various components. However, this amount of degradation is judged to be quite small in comparison to the expected structural margin of the component and is consistent with the condition found during the previous inspections in 2RF08. As a result of the data obtained during the steam drum inspection, there were no immediate recommendations made regarding any actions that should be taken prior to restart of Comanche Peak Unit 2. Based upon the inspections performed during 2RF17, no tubes exhibited degradation in excess of the CM limits. No tubes required in situ pressure testing. Therefore, the SG performance criteria for structural and leakage integrity as outlined in NEI 97-06 were satisfied for the previous operating cycle.

e. The Primary to Secondary Leakage Rate Observed During the plant Cycle 17 operation, no primary-to-secondary leakage was detected based on N-16 monitors, condenser off gas monitors, or grab sample measurements. Further, none of the eddy current indications were significant enough to cause primary-to-secondary leakage (all indications had depths below the CM limit). Hence, leakage integrity was maintained during Cycle 17.
f. Results of Monitoring for Slippage Tube slippage monitoring is required to support implementation of the H* alternate repair criteria and is performed through the course of routine bobbin coil inspections as planned by the SG Program. Bobbin coil inspections were not planned and performed during 2RF17 and therefore full slippage monitoring was not performed.

However, the hot leg top of tubesheet +POINT probe inspections can detect if tube slippage has occurred. Tube slippage was not reported during the +POINT probe inspection programs. 15 of 16

Enclosure with TXX-19063 Section 3: Indication Listing Table 7 below summarizes of indications for 2RF17 for the existing degradation mechanism for Foreign Object Wear. No other Degradation Mechanism was observed in 2RF17. Table 7 Summa of Foreign Ob"ect Wear Indications Reported in 2RF17 2RF14 2RF16 2RF17 Depth Depth Depth SG OUTAGE Ind Loe lnchl (%TW) (%TW) (%TW) Crlen RF17 PCT C6 61 2-04 2RF17 PCT C6 0.42 71 171 Note 1: Sizing data based on ETSS 96911.1. Note 2: No degradation was reported during 2RF16. Historical data review in 2RF17 showed a precursor signal present at 2RF16 with little to no change. 16 of 16}}

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