ML25251A028

CC2R26 180-Day Steam Generator Report

ML25251A028
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Site:	Calvert Cliffs
Issue date:	09/08/2025
From:	Constellation Energy Generation
To:	Document Control Desk
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TS 5.6.9
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Calvert Cliffs Nuclear Power Plant Unit 2 Steam Generator Tube Inspection Report Refueling Outage 26 CC2R26

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 2 of 24 Calvert Cliffs Nuclear Power Plant (CCNPP) Unit 2 Steam Generator Tube Inspection Report Introduction CCNPP Unit 2 Technical Specification (TS) 5.6.9, Steam Generator Tube Inspection Report, states A report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with the Specification 5.5.9, Steam Generator (SG) Program." This enclosure provides the 180-day report with the Unit 2 TS 5.6.9 reporting requirements in accordance with References 3. Each CCNPP Unit 2 TS 5.6.9 reporting requirement is listed below along with the associated information based on the inspection performed during the CCNPP Unit 2 February 2025 refueling outage (CC2R26). The 180-Day report will follow the template provided in Appendix G to the Electric Power Research Institute (EPRI) Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines (Reference 2), which provides additional information beyond the CCNPP Unit 2 TS 5.6.9 reporting requirements.

Note: Based on NRC approval (Reference 1) TSTF-577 was implemented at CCNPP on November 15, 2023.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 3 of 24

1. Design and operating parameters Calvert Cliffs Nuclear Power Plant Unit 2 (CCNPP2) has two recirculating steam generators designed and fabricated by Babcock and Wilcox (B&W) of Cambridge, Ontario, Canada. These replacement steam generators (RSGs), SG21 and SG22 were installed in 2003.

Table 1: CCNPP Steam Generator Design and Operating Parameters SG Model / Tube Material /

Number of SGs per Unit Babcock & Wilcox (Canada) Replacements / Alloy 690TT / 2 Number of tubes per SG /

Nominal Tube Diameter / Tube Thickness 8471 / 0.750 in. / 0.042 in Support Plate Style / Material Lattice Tube Support Grids and Fan Bars / 410 stainless steel Last Inspection Date Feb 2025 Effective full power months (EFPM) Since Last Inspection 67.6 EFPM [5.63 effective full power years (EFPY)]

(from CC2R23 to CC2R26)

Total Cumulative SG EFPY 24.41 (as of CC2R26)

Mode 4 Initial Entry March 20th, 2025, from CC2R26 Observed Primary-to-Secondary Leak Rate No observed leakage Nominal Thot at Full Power Operation 595°F Loose Parts Strainer Calvert Cliffs steam generators have no loose parts straining device Degradation Mechanism Sub-Population Tubes located on the periphery of the tube bundle are in the highest crossflow region and were considered in the CC2R25 Degradation Assessment to be more susceptible to foreign object wear.

SG program guideline deviations since last Inspection None SG Schematic See Figure 1

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 4 of 24 Figure 1: Tube Support Arrangement for CCNPP B&W Replacement SGs Notes:

TEC - Tube End Cold Leg TEH - Tube End Hot Leg TSC - Top-of-Tubesheet Cold Leg TSH - Top-of-Tubesheet Hot Leg 01C - 07C - Lattice Grid Tube Supports on Cold Leg side 01H - 07H - Lattice Grid Tube Supports on Hot Leg side F01 - F12 - U-Bend Fan Bar Tube Supports

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 5 of 24

2. The scope of the inspections performed on each SG (TS 5.6.9.a) and if applicable, a discussion of the reason for scope expansion Primary Side Eddy Current Scope The following inspections were performed during CC2R26 to ensure that 100% of the tubes were inspected during the period as required by TS 5.5.8.d.2 Bobbin Probe Eddy Current Testing (ECT) Examinations:

o 100% of the in-service tubes will be inspected full length, tube-end hot (TEH) to tube-end cold (TEC).

Array Probe ECT Examinations:

o 100% (X-Probe) examination on the Hot and Cold Legs from the first support to the tube end for potential foreign objects and associated wear.

o 2-tube bounding of legacy foreign objects identified in CC2R26 Degradation Assessment.

Special Interest Examinations o 100% of dings 3V (Array) o Bobbin I-codes (Array) o Array I-codes (+Point')

o Bobbin Possible Loose Part (PLP) indications (Array) o Bobbin new Foreign Object Wear (FOW) indications (Array) o 2-tube bounding of confirmed PLP, new FOW indications, or new tubes associated with foreign objects (Array) o Legacy FOW o All existing and new PRX indications (Array) o All lattice grid wear indications in each SG (Array) o Additional indications as identified by CCNPP-2 engineering and/or tube integrity engineering (TIE)

There was no scope expansion required or performed during the CC2R26 eddy current inspections.

Primary Side Visual Inspection Scope The primary side channel head (hot and cold leg) of both steam generators was visually inspected using a remote operated camera in accordance with CCNPP inspection procedures. The channel head general area and cladding was inspected for gross defects such as holes or breaches that would expose carbon steel base material under the cladding, rust colored discoloration or stains visible on cladding surface, and channel head cladding degradation such as cracks or significant deformation.

The tubesheet, tube ends, and tube plugs were inspected for the following: cracking, degradation, water leakage, boron deposits, and tube sheet or tube end deformation. No degradation was observed in any of these areas in either steam generator.

As part of the channel head inspection, the divider plate was also visually inspected from both hot and cold legs using a remote camera specifically looking for the following: cracks on the divider plate surface, surface deformation, foreign material that may mask any degradation, and any other degradation. Special attention was given when inspecting the weld deposit seat bar, divider plate weld, divider plate corner windows, and the divider plate weld heat affected zone. No degradation

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 6 of 24 was observed in any of these areas in either steam generator.

Secondary Side Inspection Scope Secondary side inspections (SSI) were performed with a variety of remote tooling. For each steam generator, a visual inspection (top of tubesheet) was performed after sludge lancing including:

Assessment of sludge conditions (both H/L and C/L) to verify lancing effectiveness 100% visual inspection of the annulus and NTL to a minimum of 6 tubes deep Blowdown and drain holes Shroud supports (as accessible from the TTS annulus)

Underside of the 1st lattice (as accessible from the no-tube lane)

Foreign Object Search and Retrieval (FOSAR) on previously identified foreign objects and PLPs as well as any new PLPs or foreign object wear as directed by Constellation Engineering and Framatome TIE.

A steam drum and upper internals inspection was performed on SG21. The steam drum and upper internals inspection included:

Upper Internals Visual Inspection o Primary moisture separators o Secondary moisture separators o Steam outlet venturi o Secondary deck seal skirt o General area structures, hatches, and welds o Fan bars and associated support structures Manway sealing surface inspection

3. The nondestructive examination techniques utilized for tubes with increased degradation susceptibility (TS 5.6.9.b)

Tubes located on the periphery of the tube bundle are in the highest crossflow region and were considered in the Degradation Assessment to be more susceptible to foreign object wear, especially near the tubesheet where most foreign objects are located. As a compensatory measure, tubes in this region were tested with an array (X-probe) which has increased sensitivity for detection of foreign objects and foreign object wear close to the tubesheet. This scope encompassed 100% of the hot and cold leg tubes from the tube end to the 1st tube support (01C/01H).

4. For each degradation mechanism found: The nondestructive examination technique utilized (TS 5.6.9.c.1)

Steam Generator eddy current examination techniques used (see Table 2 below) were qualified in accordance with Appendix H or Appendix I of the EPRI PWR SG Examination Guidelines (Reference 3). Each examination technique was evaluated to be applicable to tubing and the degradation mechanisms found in the CCNPP SGs during CC2R26.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 7 of 24 The bobbin probe was used as the primary means of detecting tube degradation except for loose parts/wear located between the Top of Tubesheet (TTS) and the first lattice support. At this location, the Array probe was used for the primary means of detection, along with detection of TTS expansion transition Intergranular Attack / Stress Corrosion Cracking (IGA/SCC) and pitting (proactive examinations). The rotating coil probe was used primarily as a diagnostic and sizing tool for indication characterization.

Table 2: Non-Destructive Examination (NDE) Techniques for Sizing Each Existing Degradation Mechanism Found During CC2R26 Location Degradation Mechanism Orientation Probe EPRI ETSS1 Fan Bar (U-bend)

Wear Vol Bobbin I-96041.1 Rev 8 Lattice Grid (Horz. Support)

Wear Vol Bobbin 96004.1 Rev 14 Foreign Object at top of tubesheet or lattice grid Wear Vol Array 17901. Rev 0 19706.1 Rev 0

1. ETSS - Examination Technique Specification Sheet

5. For each degradation mechanism found: The location, orientation (if linear), measured size (if available), and voltage response for each indication. For tube wear at support structures less than 20 percent through-wall, only the total number of indications needs to be reported (TS 5.6.9.c.2)

Three degradations mechanisms were confirmed to be present in the CCNPP Unit 2 SGs. These were: 1) fan bar wear, 2) lattice grid support wear, and 3) foreign object wear. No other degradation mechanisms, including tube-to-tube wear, were detected. Table 3 provides the number of indications reported during the CC2R26 inspection.

Table 3: Number of Indications Detected for Each Degradation Mechanism in CC2R26 Degradation Mechanism SG21 SG22 Total Indications Indications Fan Bar Wear 131 315 446 Lattice Grid Support Wear 2

4 6

Foreign Object Wear 16 11 27 Table 4 provides a listing of all the fan bar wear indications 20% through wall (TW) or greater reported during the CC2R26 inspection including the measured depths from the array probe.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 8 of 24 Table 4: CC2R26 Fan Bar Wear Indications >20%TW SG Row Col Location Array Depth

(%TW)

Voltage (Bobbin)

SG21 44 6

F06 +1.93 24 0.48 SG21 104 88 F06-0.75 20 0.38 SG21 108 76 F06+1.57 23

.83 SG22 79 93 F08+1.77 26 0.59 SG22 87 83 F07-0.08 24 0.51 SG22 91 65 F08+0.72 23 0.48 SG22 103 67 F06-0.78 21 0.39 SG22 107 81 F06-0.84 22 0.44 SG22 108 82 F07+0.68 21 0.39 SG22 108 86 F06-1.24 25 0.66 SG22 109 77 F06-0.86 22 0.45 SG22 109 79 F06-0.79 24 0.50 SG22 111 73 F06-1.28 26 0.56 SG22 111 75 F06-0.84 20 0.37 SG22 111 77 F06-0.81 25 0.55 SG22 113 77 F06-0.82 27 0.62 SG22 113 81 F06-1.23 21 0.39 SG22 114 84 F06-1.21 22 0.42 SG22 116 82 F07+1.22 20 0.36 SG22 123 83 F07+0.08 26 1.20 Six indications of wear related to the lattice grid supports were reported during the CC2R26 outage. All of these indications were inspected with array probes to confirm that the morphologies of the indications were consistent with lattice grid wear and not some other damage mechanism such as foreign object wear. No lattice grid wear indications were reported to be greater than 20%TW. The deepest lattice grid wear indication reported was 15% TW in SG

22.

Table 5 provides a listing of all the foreign object wear indications reported during the CC2R26 inspection including the measured voltages, depths, and measured dimensions using the array probe. Twenty-seven (27) foreign object wear indications were detected in.3 tubes. Twenty of the 27 indications were reported in previous outages, since the parts were no longer present from previous outages, as expected, there was no noticeable change in the depths of these indications.

Indications during CC2R26 were detected and sized using Array techniques ETSS 17901.1 (26 flaws) and ETSS 17906.1 (1 flaw). This flaw (SG22 67-141 TSH+0.15) was sized with ETSS 17906.1 based on the flaw morphology based on data analyst review of the flaw. All flaws met condition monitoring

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 9 of 24 as shown on Figure 4 and Figure 5. On the initial NDE screening of one flaw, SG22 3-127 01C 0.26, condition monitoring was met but was close to the condition monitoring limit as shown in Figure 4.

Line by Line Array profile data was used in conjunction with analytical methods described in the SG Integrity Assessment Guidelines Section 5.1.5 (Reference 2) to develop a structurally equivalent flaw for condition monitoring evaluation purposes, Figure 6.

All but one of these foreign object wear indications were sized below the plugging limit. Due to the foreign object being present within the first lattice grid support one tube was plugged for meeting the 40%TW Tech. Spec. plugging limit (Tech Spec 5.5.9.c) and two adjacent tubes were preventatively plugged. The other 19 tubes showing FOW indications were returned to service with no part present. Table 7 details the tubes plugged during CC2R26.

Table 5: CC2R26 Foreign Object Wear Indications SG Row Col Location CC2R26 Array Depth (%TW)

Axial Extent (Inches)

Circ. Extent (Inches)

Voltage (Array) 21 12 66 TSH +0.53 21 0.35 0.29 0.43 21 12 66 TSH +0.2 26 0.25 0.29 0.65 21 12 162 TSH +0.15 30 0.18 0.29 0.87 21 13 65 TSH +0.13 22 0.22 0.37 0.46 21 14 66 TSH +0.56 16 0.28 0.37 0.24 21 14 66 TSH +0.58 16 0.25 0.29 0.24 21 72 146 TSH +0.33 33 0.3 0.37 1.04 21 75 147 TSH +18.01 18 0.35 0.44 0.30 21 77 147 TSH +17.69 20 0.28 0.29 0.38 21 77 149 TSH +20.46 21 0.3 0.44 0.43 21 121 117 TSH +0.68 21 0.25 0.29 0.44 21 129 75 TSH +4.73 29 0.35 0.37 0.79 21 130 76 TSH +4.89 30 0.33 0.37 0.84 21 137 73 TSC +15.02 21 0.40 0.29 0.41 21 137 75 TSC +14.72 15 0.45 0.29 0.22 21 137 75 TSC +14.42 20 0.45 0.29 0.40 22 2

126 01C -0.28 27 0.28 0.22 0.73 22 2

126 01C +0.28 24 0.28 0.22 0.54 22 3

127 01C +0.26 54 0.6 0.44 2.93 22 14 4

TSC +0.56 28 0.35 0.29 0.74 22 18 2

TSC +0.18 20 0.22 0.29 0.39 22 67 141 TSH +0.15 28 0.50 0.29 1.72 22 82 42 04H -1.72 30 0.35 0.22 0.90 22 112 82 04H +38.28 19 0.20 0.29 0.36 22 124 116 TSC +12.79 15 0.38 0.29 0.23 22 126 116 TSC +12.58 19 0.30 0.37 0.35 22 126 116 TSC +12.86 33 0.30 0.29 1.03

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 10 of 24

6. For each degradation mechanism found: A description of the condition monitoring assessment and results, including the margin to the tube integrity performance criteria and comparison with the margin predicted to exist at the inspection by the previous forward-looking tube integrity assessment (TS 5.6.9.c.3). Discuss any degradation that was not bounded by the prior operational assessment in terms of projected maximum flaw dimensions, minimum burst strength, and/or accident induced leak rate. Provide details of any in situ pressure test.

A condition monitoring (CM) assessment was performed as required by the CCNPP SG program.

The tube degradation detected during the CC2R26 inspection was due to fan bar wear, lattice grid wear, and foreign object wear. The deepest indication for each mechanism met condition monitoring analytically as shown in Figures 2, 3, 4 and 5.

The deepest flaws have a depth less than the conservatively determined CM limit for all degradation mechanisms; therefore, the structural integrity performance criterion was met for the operating interval prior to CC2R26.

A summary of the CM results from CC2R26 as compared to the Operational Assessment (OA) predictions from the most recent prior inspection (CC2R23) is provided in Table 6.

Figure 2: Condition Monitoring Results for Fan Bar Wear An assumed bounding length equal to the fan bar thickness was used for all bobbin exams

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 11 of 24 Figure 3: Condition Monitoring Results for Lattice Grid Wear (All SGs)

Figure 4: Condition Monitoring Results for Foreign Object Wear ETSS 17901.1 (All SGs)

An assumed bounding length equal to the lattice grid thickness was used for all bobbin exams

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 12 of 24 Figure 5: Condition Monitoring Results for Foreign Object Wear: ETSS 17906.1 (SG22)

Figure 6: Structurally Equivalent Flaw: SG22 3-127 01C +0.26 Array Line by Line Data

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 13 of 24 Table 6: Comparison of Prior OA Projections to As-Found Results Parameter CC2R26 Projection CC2R26 As Found Inspection Interval 6.0 EFPY 5.63 EFPY Fan Bar Wear Maximum Depth 39.5%TWD 27%TWD Fan Bar Wear Upper 95th Growth Rate 0.8%TWD/ EFPY 0.89%TWD/ EFPY Lattice Grid Wear Maximum Depth 34.5%TWD 15%TWD Lattice Grid Wear Upper 95th Growth Rate 2.0%TWD/ EFPY 0.93%TWD/ EFPY Foreign Object Wear Maximum Depth

< 34.8%TWD1 54%TWD1 Notes:

1.

54%TWD was found at 01C support. The next highest FOW was 33% at the TTS. The number estimated for CC2R26 by the previous CMOA was calculated for a foreign object at TTS. The OA projection made in CC2R23 was bounding of TTS FOW at CC2R26.

Volumetric wear indications will leak and burst at essentially the same pressure; therefore, accident-induced leakage integrity is also demonstrated. Operational leakage integrity was demonstrated by the absence of any detectable primary-to-secondary leakage during the operating interval prior to CC2R26. Because tube integrity was demonstrated analytically, in-situ pressure testing was not required nor performed during CC2R26. There were no tube pulls planned or performed during CC2R26.

7. For each degradation mechanism found: The number of tubes plugged during the inspection outage (TS 5.6.9.c.4). Also, provide the tube location and reason for plugging.

A total of 3 tubes were plugged at CC2R26, Summary of degradation mechanism and location of plugs are shown in Tables 7.

Table 7: Calvert Cliffs Unit 2 - 2R26 - S/G 22 PLUG LIST SG Row Col Location Reason for Repair 22 1

127 01C-0.33 PLP - Preventative 22 2

126 01C +0.28/-0.28 FOW - Preventative 22 3

127 01C +0.26 TW >40% TS Plugging Limit

8. The repair methods utilized, and the number of tubes repaired by each repair method (TS 5.6.9.c.5).

No tubes were repaired during CC2R26.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 14 of 24

9. An analysis summary of the tube integrity conditions predicted to exist at the next scheduled inspection (the forward-looking tube integrity assessment) relative to the applicable performance criteria, including the analysis methodology, inputs, and results (TS 5.6.9.d). Include the effective full power months of operation permitted for the current operational assessment.

Summary Based on the application of conservative fan bar, lattice grid, and foreign object wear growth rates, the condition of the CCNPP SG tubes has been analyzed with respect to continued operability of the SGs without exceeding the SG tube integrity performance criteria at the next scheduled SG eddy current inspection no later than CC2R29.

Fan Bar Wear OA Due to the small growth rate noted at multiple consecutive inspections, a deterministic approach is appropriate for performing the fan bar wear operational assessment.

For fan bar wear, the deepest indication returned to service was 27%TW. The NDE sizing parameters for ETSS I-96041.1 are a slope of 0.94, an intercept of 5.43, and a standard error of 3.41%TW. Using the slope and intercept, a best estimate real depth of 30.81%TW is obtained for an indication with a measured depth of 27%TW.

The standard error of 3.41%TW from ETSS I-96041.1 is the technique uncertainty. Further adjusting this value upward to an upper 95th percentile gives an NDE uncertainty of 5.609%TW (3.41 x 1.645).

Adding this uncertainty to the best estimate value of 30.81%TW from the previous paragraph yields a bounding real depth of 36.42%TW returned to service.

This hypothesized real depth of 36.42%TW must then be grown at an upper 95th growth rate for the next 8.0 EFPY and the upper 95th percentile growth rate is 1.1%TW per EFPY. Applying a growth of 8.8%TW (1.1 x 8.0) gives a bounding real depth at the end of the upcoming inspection interval of 45.22%TW.

For an assumed bounding length of 3.375, the structural limit (SL) for this hypothesized limiting flaw is 48.6%TW. The structural limit includes uncertainties for material properties and the burst pressure relationship and is the allowable real depth for a flaw of a given length. Since the projected real depth of 45.22%TW is less than the structural limit of 48.6%TW, there is reasonable assurance that structural integrity will be maintained until the next scheduled inspection, (CC2R29).

The projected EOC depth is believed to be very conservative since it pairs the deepest indication returned to service in CC2R26 with upper 95th percentile values for both NDE uncertainties and growth rates.

Lattice Grid Wear OA Unlike fan bar wear, there is too little data to calculate a reliable upper 95th percentile growth rate for lattice grid wear. All of the reported lattice grid wear indications were reported in the previous CC2R23 inspection. The largest growth rate among these indications was 2.0%TW per EFPY. Due to the limited population and the low growth rates of the existing indications, an assumed growth rate of 2.0%TW per EFPY will be used in the OA.

The measured lengths of lattice grid flaws are all less than 3.15 inches. Since the high bar lattice grids are 3.15 inches tall, a bounding flaw length of 3.15 inches have been used in the analysis.

Using ETSS 96004.1, a best estimate real depth is obtained as follows. The deepest lattice grid wear

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 15 of 24 indication returned to service measured 15%TW. The NDE sizing parameters for ETSS 96004.1 are a slope of 0.99, an intercept of 2.93, and a standard error of 4.18%TW. Using the slope and intercept, a best estimate real depth of 24.66%TW is obtained for an indication with a measured depth of 15%TW.

The standard error of 4.18%TW from ETSS 96004.1 is the technique uncertainty. Further adjusting this value upward to an upper 95th percentile gives an NDE uncertainty of 6.88%TW (4.18 x 1.645).

Adding this uncertainty to the best estimate value of 24.66%TW from the previous paragraph yields a bounding real depth of 31.54%TW returned to service.

This hypothesized real depth of 24.66%TW must then be grown at an upper 95th growth rate for the next 8.0 EFPY. As discussed above, a growth rate of 2.0%TW per EFPY will be used. Applying a growth of 16.0%TW (2.0 %TW/EFPY x 8.0 EFPY) gives a bounding real depth at the end of the upcoming inspection interval of 40.66%TW.

For a flaw with an assumed bounding length of 3.15 inches, the structural limit is 48.7%TW. Since the projected depth of 40.66%TW is less than this value, there is reasonable assurance that structural integrity will be maintained until the next scheduled inspection.

Tube Wear from Existing, Remaining, and New Foreign Objects OA The maximum wear rate observed for foreign objects over the previous operating interval can be used to calculate a maximum run time for newly initiated foreign object wear. The deepest new foreign object wear scar was 47.3%TW (after line-by-line sizing), suggesting a growth rate of 8.4%TW/EFPY over the previous operating interval of 5.63 EFPY. Assuming a similar growth rate for a newly initiated wear scar and a structural limit of 51%TW, which is associated with a conservative scar length of 1.0 and a limited circumferential extent of less than 135° a maximum run time can be calculated.

The maximum calculated run time of 6.07 EFPY (51%TW / (8.4%TW / EFPY)) has been established, based on a wear rate of 8.4%TW/EFPY and a structural limit of 51%TW. There is reasonable assurance that foreign object wear associated with the observed parts will not exceed the performance criteria prior to the next inspection (CC2R29) of the Calvert Cliffs Unit 2 steam generators.

For those objects not detected or those objects that enter the bundle during operation, there is experience that the plant can operate multiple cycles with foreign objects in the bundle without tube wear exceeding the condition monitoring limit or leakage occurring. As such, there is reasonable assurance that foreign objects will not cause wear that exceeds the structural integrity performance criteria prior to the next tube examination in each steam generator.

Because no wear exceeding the structural criteria is expected, there is reasonable assurance that the operational leakage and accident leakage performance criteria will not be exceeded by foreign object wear prior to the next tube examination in each steam generator (CC2R29).

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 16 of 24 Table 8: Comparison of OA Projections at Next SG Inspection to Structural Limits Degradation Mechanism (wear)

Maximum depth (%) Predicted after 4 cycles (8.0 EFPY)

Structural limit depth (%)

Fan Bar support 46 48.6 (3.375 Length)

Lattice Grid support 41 48.7 (3.15 Length)

Existing FO Wear No Growth (FO removed) 51.0 (1.0 Length)

Remaining FOs All FOs identified capable of wear were removed New FOs

<51.0 for 3-cycles (~6.0 EFPY)

10. The number and percentage of tubes plugged to date, and the effective plugging percentage in each SG (TS 5.6.9.e).

Table 9 shows the number of tubes plugged as of the CC2R26 outage and the percentage of tubes currently plugged (total and effective). No sleeves have been installed in the CCNPP replacement SGs. Three tubes were plugged in SG 22 during CC2R26, SG22 3-127 for TW>40%, SG 22 2-126 (PLP, Single Volumetric Indication (SVI)) and SG 22 1-127(PLP Only) during CC2R26. Table 9: Tube Plugging to Date (Number and Percentage per SG) (TS 5.6.9.e)

Table 9: SG Tube Plugging Profile SG21 SG22 Total Plugged prior to CC2R26 37 32 69 Plugged during CC2R26 0

3 3

Total Plugged through CC2R26 37 35 72 Total/Effective Percent Plugged through CC2R26 0.44%

0.41%

0.42%

11. The results of any SG secondary-side inspection (TS 5.6.9.f). The number, type, and location (if available) of loose parts that could damage tubes removed or left in service in each SG.

Secondary Side Visual Inspections of Tubesheet & FOSAR and Steam Drum Secondary side tubesheet visual inspections were performed following sludge lancing activities in both SGs. High flow regions of the annulus, no tube lane and periphery (a minimum of 8 tubes deep) were visually inspected for foreign material. Additionally, multiple columns for the full depth of the tube bundle interior (kidney region) were evaluated for sludge lancing effectiveness and sludge accumulation.

Foreign object search and retrieval (FOSAR) was performed on a variety of foreign objects identified from visual inspections as well as ECT PLPs and FO Wear indications as summarized in Table 10.

All metallic or potential objects that could cause wear were removed from SG21 and SG22 during CC2R26.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 17 of 24 Table 10: Foreign Object Search and Retrieval Summary SG Row Col Location Ref ID CC2R26 Disposition Material Status 21 11 161 TSH 1

Legacy FOW without growth (no part present). No PLPs detected on bounding tubes. No further actions required in CC2R26.

Weld Slag Removed 21 77 151 TSH 3

Legacy FOW. No PLPs detected on bounding tubes. No further actions required in CC2R26.

Wire Removed 21 11 1

TSC 4

Legacy - Surrounding inservice tubes are No Degradation Detected (NDD), no wear or PLPs. No further actions required in CC2R26.

Weld Slag Removed 21 38 6

TSH 5

Legacy - Surrounding tubes are NDD, or PLPs. No further actions required in CC2R26.

Metal Removed 21 77 149 TSH 7

Legacy FOW with part removed. No PLPs on affected/bounding tubes.

Legacy FOW on 77-149 shows no growth. No further actions required in CC2R26.

Wire Removed 21 12 162 TSH 8

Legacy FOW with part removed. No PLPs on affected/bounding tubes.

Legacy FOW on 12-162 shows no growth. No further actions required in CC2R26.

Weld Slag Removed 21 72 146 TSH 17 Legacy foreign object wear (no part present). Surrounding tubes not affected by wear are NDD without PLP. No further actions required in CC2R26.

Wire Removed 21 90 26 TSH 19 Legacy foreign object wear location. All bounding tubes are NDD. No further actions required in CC2R26.

Weld Slag Removed 21 131 75 TSH 36 Legacy - No part observed by SSI in CC2R26. Affected/bounding tubes did not contain PLPs. No further actions required in CC2R26.

Weld Slag Removed 21 133 77 TSH 38 Legacy part was verified not there by SSI in CC2R26. Affected tube was NDD. No further actions required in CC2R26.

Unknown Removed 21 131 93 TSC 41 Legacy Part not found by SSI CC2R26.

Surrounding inservice tubes are NDD. No further actions required in CC2R26.

Weld Slag Removed 21 135 89 TSC 44 Legacy part - Affected tubes previously plugged. No wear or PLPs on surrounding tubes. No further actions required in CC2R26.

Metal Removed

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 18 of 24 21 135 91 TSC 45 Legacy part not found in CC2R26.

Affected/bounding tubes are NDD, no wear or PLPs. No further actions required in CC2R26.

Metal Removed 21 131 97 TSC 47 Legacy part - SSI confirmed FO is no longer in or adjacent to the described location. Affected tubes are NDD. No further actions required in CC2R26.

Metal Removed 21 14 64 TSH 177 Legacy item in the stay well region. LPW with no PLPs. No further actions required in CC2R26.

Unknown Removed 21 57 81 TSH 275 Legacy object confirmed fixed in hard deposit. There is no change in fixity and location of part. No wear on affected or bounding tubes. No further actions required in CC2R26.

Flex gasket Remains 21 110 126 TSH 293 Legacy part - visual exam confirmed part remains unchanged and has not moved.

Affected/bounding tubes are NDD. Part is acceptable to remain in the SG. No further actions required in CC2R26.

Metal Remains 21 121 117 TSH 348 Legacy FOW. Bounding tubes are NDD or PLPs. No further actions required in CC2R26.

Unknown Removed 21 137 75 TSC 349 Legacy FOW. No PLPs found during outage. Bounding tubes are NDD. No growth noted. No further actions required in CC2R26.

Unknown Removed 21 18 68 TSH 350 New part found in CC2R26. No PLPs remain in affected/bounding tubes. No further actions required in CC2R26.

Flex gasket Removed 21 24 74 TSH 351 New part found in CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 44 10 TSH 356 New part found CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 51 31 TSH 357 New part found CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 82 30 TSH 360 New part found CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 112 36 TSH 361 New part found in CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 121 49 TSH 362 New part found in CC2R26.

Affected/bounding tubes NDD. No Metal Removed

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 19 of 24 further actions required in CC2R26.

21 136 70 TSH 363 New part found in CC2R26.

Affected/bounding tubes NDD. No further actions required in CC2R26.

Soft Metal Removed 21 125 77 TSH 364 New part found in CC2R26. New FOW on bounding tubes. No further actions required in CC2R26.

Flex Gasket Removed 21 132 74 TSH 365 New part found in C2R26. ECT is NDD on these affected tubes. No further action required.

Metal Removed 21 114 128 TSC 367 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Metal Curl Removed 21 36 148 TSC 368 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 128 112 TSH 370 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 118 86 TSH 373 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Metal Curl Removed 21 133 105 TSH Annulus 374 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 130 110 TSH Annulus 375 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex & Wire Removed 21 17 31 TSC 377 New part not found during FOSAR.

Affected/bounding tubes are NDD or PLPs. No further actions CC2R26.

Unknown Removed 21 11 35 TSC 378 New part not found during FOSAR.

Affected/bounding tubes are NDD without wear or PLPs. No further actions CC2R26.

Unknown Removed 21 123 87 TSC 380 New part found in CC2R26.

Affected/bounding tubes are NDD. No additional actions required CC2R26.

Fibrous Removed 21 53 29 TSC 381 New part found in CCR226. Flex embedded in deposit Material.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex Gasket Remains 21 88 130 TSC 384 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Flex Gasket Removed 21 123 87 TSH 385 New part found in CC2R26.

Affected/bounding tubes are NDD. No further actions required in CC2R26.

Wire Removed

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 20 of 24 22 14 4

TSC 2

Legacy FOW, no part visible in CC2R26.

Bounding tubes are NDD. No further actions required in CC2R26.

Unknown Removed 22 126 116 TSC 4

No part visible in CC2R26. Bounding tubes are NDD. No further actions required in CC2R26.

Unknown Removed 22 125 97 TSC 32 Legacy wire found in CC2R23. All tubes bounding plugged tubes NDD. No further actions required in CC2R26.

Wire Removed 22 8

2 TSC 62 Legacy PLP call. Nothing seen with SSI or ECT inspection. No further actions required in CC2R26 PLP Removed 22 60 118 TSH 76 Legacy LPS. Affected/bounding tubes are NDD. No further actions required in CC2R26 PLP Removed 22 50 90 TSH 113 Legacy PLP not found in CC2R26.

Affected/bounding tube are NDD. No further actions required in CC2R26 PLP Removed 22 129 91 TSC 140 Legacy PLP not found in CC2R26.

Affected/bounding tube are NDD. No further actions required in CC2R26.

PLP Removed 22 133 77 TSH 179 Legacy part found (same location) in CC2R26. Affected/bounding tubes are NDD. No further actions required in CC2R26.

Metallic Cube Remains 22 17 1

TSC 187 Legacy LPW not found in CC2R26. All tubes are free from PLPs. Bounding tubes are NDD. No further actions required in CC2R26.

Unknown Removed 22 112 66 TSH 200 Legacy part found in CC2R26.

Affected/bounding tubes are NDD. No further actions in CC2R26 Flexitallic Gasket Removed 22 131 69 TSH 202 Legacy part not located in CC2R26.

Affected/bounding tubes are NDD no PLP. No further actions recommended for CC2R26 Metal Removed 22 93 117 TSH 248 Legacy PLP identified in CC2R26, with no SSI performed. There is no wear on the affected and bounding tubes in CC2R26. No further actions required in CC2R26 PLP Remains 22 67 141 TSH 253 New part found in CC2R26. ECT shows LPW only on 67-141. Remaining tubes are NDD. No further actions required in CC2R26 Flex Gasket Removed 22 84 138 TSH 254 New - No part found CC2R26. Affected tubes have LPS with no wear. Bounding tubes are NDD without wear. No further actions required in CC2R26.

PLP Removed

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 21 of 24 22 89 115 TSH 255 New PLP. Affected tube and bounding tubes are NDD without wear. No further actions required in CC2R26 Unknown Remains 22 6

12 TSC 256 New part found in CC2R26. Affected and bounding tubes are NDD without wear.

No further actions required in CC2R26 Wire Removed 22 82 42 04H 257 Legacy LPW with no PLP present.

Affected/bounding tubes are NDD. No further actions required in CC2R26 Unknown Removed 22 112 82 04H 258 Legacy LPW with no part present.

Affected and bounding tubes are NDD without wear. No further actions required in CC2R26 Unknown Removed 22 2

126 01C 259 New part found in CC2R26. Two tubes with SVIs as well as adjacent tube with PLP have been plugged. No further actions required in CC2R26.

Unknown Removed 22 70 70 TSC 260 Legay PLP. Affected and bounding tubes are NDD with no wear. No further actions required in CC2R26.

Unknown Remains 22 137 77 TSC 261 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 104 36 TSC 262 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 49 9

TSH 266 New part found in CC2R26. Affected and bounding tubes NDD without wear or PLPs. No further actions required in CC2R26.

Flex Gasket Removed 22 95 31 TSH 267 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 125 73 TSH 269 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 91 139 TSH 270 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 98 128 TSH 272 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 100 124 TSH 273 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in Flex Gasket Removed

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 22 of 24 CC2R26.

22 107 133 TSH 274 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 113 119 TSH 275 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Foil Removed 22 119 123 TSH 276 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Flex Gasket Removed 22 26 96 TSH 279 New part found in CC2R26. Affected and bounding tubes are NDD with no wear or PLPs. No further actions required in CC2R26.

Flex Gasket Removed

1.

NDD - No Degradation Detected

2.

TSC - Tubesheet Cold

3.

TSH - Tubesheet Hot

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 23 of 24 Steam drum and upper internals inspection Planned steam drum and upper tube bundle inspections were performed in SG21. No evidence of degradation or structural distortion was observed in the steam drum. All of the components inspected did not show any signs of gross degradation. Based on prior inspection history and operating experience SG21 steam drum conditions are considered to be representative of the conditions in SG22.

The primary and secondary separators were examined and determined to be in good condition with no through-holes noted. This condition is typical of all secondary separators that were inspected. The separators were fabricated from carbon steel and have a minimum chromium content of 0.14% to resist Flow Accelerated Corrosion (FAC), therefore, FAC of the separators is not expected.

Based on the upper secondary side visual inspection results in SG21 inspection results there are no secondary side degraded conditions that are expected to challenge tube integrity over the next 4 cycles of operation.

Select regions of the upper tube bundle in SG21 were visually inspected, showing some deposits on the tubes, no other anomalous conditions were identified in this region.

12. The scope, method, and results of secondary-side cleaning performed in each SG Water lancing was performed in both SGs followed by secondary side visual inspections of the periphery, no-tube lane, and inner bundle passes. A total of 28 lbs. of sludge was removed both the SGs along with a variety of foreign objects such as flexitallic gaskets, weld wire, and miscellaneous small metallic pieces. Deposit removal weights are shown in Table 11.

Table 11: CC2R26 SG Deposit Removal Weights SG Weight 21 16 lbs.

22 12 lbs.

Total 28 lbs.

The eddy current bobbin probe was used to estimate the top of tubesheet sludge deposit height and the number of effected tubes.

Bobbin eddy current inspection data from the CC2R26 inspection outage will be used to complete full bundle deposit mapping at a later date.

13. The results of primary side component visual inspections performed in each SG.

Visual Inspection of Installed Tube Plugs and Tube-to-Tubesheet Welds All tube plugs (qty 69) installed prior to CC2R26 were visually inspected in both channel heads for signs of degradation and leakage. The tube-to-tubesheet welds were visually inspected during eddy current. No degradation or anomalies were found.

Steam Generator Tube Inspection Report CCNPP Unit 2 Refueling Outage 26 Page 24 of 24 SG Channel Head Bowl Visual Inspections Each SG hot and cold leg primary channel head was visually examined for evidence of breaches in the cladding or cracking in the divider-to-channel head weld and for evidence of wastage of the carbon steel channel head. No evidence of cladding breaches, wastage, or corrosion in the channel head was identified. Also, no cracking in the divider-plate-to-channel-head weld was identified.

References

1. NRC Letter To CEG, Calvert Cliffs Nuclear Power Plant, Units 1 and 2 - Issuance Of Amendment Nos. 346 and 324 RE: Adoption of TSTF-577, Revised Frequencies for Steam Generator Tube Inspections, Revision 1 (EPID L-2022-LLA-0115), Dated August 8, 2023 (ML23188A040)

2. Steam Generator Management Program: EPRI Steam Generator Integrity Assessment Guidelines, Revision 5, EPRI, Palo Alto, CA, December 2021 (EPRI Doc. No. 3002020909)

3. Steam Generator Management Program: EPRI Pressurized Water Reactor Steam Generator Examination Guidelines, Revision 8, EPRI, Palo Alto, CA, June 2016 (EPRI Doc. No.

3002007572)