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{{Adams
#REDIRECT [[ML23305A042]]
| number = ML23305A041
| issue date = 11/01/2023
| title = Updated Steam Generator Tube Inspection Report
| author name =
| author affiliation = Constellation Energy Generation, LLC
| addressee name =
| addressee affiliation = NRC/NRR
| docket = 05000456, 05000457
| license number =
| contact person =
| case reference number = BW230048
| package number = ML23305A039
| document type = Inservice/Preservice Inspection and Test Report
| page count = 1
}}
 
=Text=
{{#Wiki_filter:Enclosure 1 Braidwood Station, Unit 1 Updated Steam Generator Tube Inspection Report E 1 - 1 of 25
 
Enclosure 1 Braidwood Station, Unit 1 Updated Steam Generator Tube Inspection Report Introduction In Reference 1, Constellation Energy Generation (CEG) submitted a request for an amendment to Renewed Facility Operating License No. NPF-72 for the Braidwood Station (Braidwood), Unit 1 to adopt Technical Specifications Task Force (TSTF)-577, "Revised Frequencies for Steam Generator Tube Inspections" and Reference 2, Supplement to Application to Revise Technical Specifications to Adopt TSTF-577, "Revised Frequencies for Steam Generator Tube Inspections". Reference 1 and 2 were approved by the Nuclear Regulatory Commission (NRC) in Reference 3. As noted in Reference 2, "CEG will submit SG Tube Inspection Reports meeting the revised TS 5.6.9 requirements within 60 days after implementation of the license amendment at Braidwood." Based on NRC approval (Reference 3) TSTF-577 was implemented at Braidwood Station on September 13, 2023.
Braidwood Unit 1 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 revised 180-day report with the revised Braidwood Unit 1 TS 5.6.9 reporting requirements in accordance with References 3. Each Braidwood Unit 1 TS 5.6.9 reporting requirement is listed below along with the associated information based on the inspection performed during the Braidwood Unit 1 Cycle 23 October 2022 refueling outage (A 1 R23), which was the last inspection of the Braidwood Unit 1 replacement steam generators (Reference 4). This report follows the template provided in Appendix G to the Electric Power Research Institute (EPRI) Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines, Revision 5 (Reference 5), which provides additional information beyond the Braidwood Unit 1 TS 5.6.9 reporting requirements.
: 1. Design and operating parameters The original SGs at Braidwood Unit 1 were replaced in 1998 with four Babcock & Wilcox replacement Steam Generators (SGs), which have thermally treated Alloy 690 tubing. The SGs had operated for four fuel cycles since the previous inspection at A 1 R 19. Table 1 provides the Braidwood Unit 1 SG design and operating parameter information.
E1 - 2 of 25
 
Enclosure 1 Table 1: Braidwood Unit 1 - Steam Generator Design and Operating Parameters SG Model / Tube Material /      Babcock & Wilcox (Canada) Replacements / Alloy Number of SGs per Unit          690TT I 4                                                      I
' Number of tubes per SG I          6,633 / 0.6875 in. / 0.040 in Nominal Tube Diameter/ Tube Thickness                                                                                        :
Support Plate Style / Material  Lattice Tube Support Grids and Fan Bars/
stainless steel Last Inspection Date          i October 2022                                                    i Effective full power months    i 68.801 EFPM [5.734 effective full power years I
i (EFPM) Since Last Inspection  I (EFPY)] (from A1R19 to A1R23)                                    I i  Total Cumulative SG EFPY      I 22.71 EFPY (as of A1R23)
I i
I Mode 4 Initial Entry          I 10/18/2022 from A 1R23                                          !
Observed Primary-to-Secondary No observed leakage Leak Rate                                                                                        I Nominal Thot at Full Power      617°F Operation
: Loose Parts Strainer              Each main feedwater pump has small diameter holes in an inlet strainer to prevent the introduction of I
I                                  foreign material into the piping leading to the SGs.
i I
Degradation Mechanism            Tubes located on the periphery of the tube bundle are !
Sub-Population                  in the highest cross-flow region and were considered in i the A 1 R23 Degradation Assessment to be more susceptible to foreign object wear.
i SG program guideline deviations  None I since last Inspection i SG Schematic            -------  See Figure 1 1
I i ___________ -------- -                                                                -**-- _____I E1 - 3 of 25
 
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                            ;SC                                            TSH
                            ;[(                                          TEH Tube Support Arrangement for Braidwood Unit 1 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 01 C - 09C - Lattice Grid Tube Supports on Cold Leg side 01 H - 09H - Lattice Grid Tube Supports on Hot Leg side F01 - F1 0 - U-Bend Fan Bar Tube Supports E1 - 4 of 25
 
Enclosure 1
: 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 The following inspections were performed during A 1R23 to ensure that 100% of the tubes were inspected during the period as required by TS 5.5.9.d.2 Primary Side Eddy Current Scope:
* 100% full-length bobbin coil eddy current examination of all in-service tubes in all four SGs.
* All Hot leg Dent & Dings >2.0 volts, Plus-Point probe in all four SGs.
* 57% peripheral array (X-Probe) examination on the Hot Leg for potential foreign objects and associated wear (peripheral locations are where crossflow velocities are the highest)
* 43% of peripheral array (X-Probe) examination Cold Leg for potential foreign objects and associated wear.
There was no scope expansion required or performed during the A 1R23 eddy current inspections.
In addition to the eddy current inspections, visual inspections were also performed on both the primary and secondary sides. Primary side visual inspections included the channel head bowl cladding and the divider plate. Secondary side visual inspections were performed at the top of the tubesheet for the detection of foreign objects, assessment of hard deposit buildup in the tube bundle interior kidney region, and for determining the effectiveness of the tubesheet cleaning performed in the four SGs.
: 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 cross-flow region and were considered in the Degradation Assessment (DA) 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 57% of the hot leg tubes and 43% of the cold leg tubes from the top-of-tubesheet to the 1st tube support (01 C/01 H).
: 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 Revision 8. Each examination technique was evaluated to be applicable to the tubing and the degradation mechanisms found in the Braidwood Station Unit 1 SGs during A 1R23.
E1 - 5 of 25
 
Enclosure 1 Table 2: Non-Destructive Examination (NOE) Techniques for Each Existing Degradation Mechanism Found During A 1R23 EPRI Degradation Location                              Orientation      Probe        EPRIETSS        ETSS Mechanism Rev Fan Bar (U-bend)                                                    1-96041.1 (D)        6 Wear            Vol          Bobbin 96004.3 (D&S)        13 Lattice Grid Wear            Vol          Bobbin      96004.3 (D&S)        13 (Horz. Support)
Foreign Object at                                      Array      1790X.1 (D)          0 top of tubesheet          Wear            Vol          +Point      21998.1 (S)          4 or lattice grid                                        +Point      27902.1 (S)          2 (D) = Detection (S) = Sizing
: 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)
Volumetric wear at support structures was the primary degradation mechanism detected during the A 1 R23 inspection. The wear indications detected were located at either fan bar U-bend or horizontal lattice grid tube support structures. Table 3 provides the number of indications reported during the A 1 R23 inspection Table 3: Number of Indications Detected for Each Degradation Mechanism in A1R23 Degradation              1ASG          1BSG          1C SG        1DSG          Total Mechanism Indications  Indications  Indications  Indications Fan Bar (U-bend            8            18            39          21          86 support) wear Lattice grid                3            4            3            1            11 Support Wear Foreign Object              5              1            10            0            16 Wear A detailed listing of all the Fan Bar wear indications reported during the A 1 R23 inspection including the measured voltages and depths from the bobbin coil is provided in Attachment A (same data as submitted under Reference 4).
E1 - 6 of 25
 
Enclosure 1 Table 4 provides a listing of all the lattice grid wear indications reported during the A 1 R23 inspection including the measured depths from the bobbin coil.
Table 4: A1R23 Lattice Grid Wear Indications A1R23 Voltage SG        Row        Col        Location    Depth (Bobbin)
(3/4TW) 1A        39        70      01H-1.16      11          0.64 1A        75        108      07H -1.22      5          0.21 1A      118        71      01C +0.99      6          0.31 1B        47        24      08H -1.43      6          0.27 1B        87        24      01C -0.82      9          0.43 1B        90        107      07H +0.48      9          0.49 1B      119        70      02C +0.76      11          0.72 1C        9        92      05C -1.62      8          0.42 1C        47        56      05H -1.68      6          0.28 1C        73        90      05H +1.41      4          0.20 1D        41        70      08H -1.61      6          0.22 Table 5 provides a listing of all the foreign object wear indications reported during the A 1 R23 inspection including the measured voltages and depths from the plus-point probe.
Indications of tube wear at support structures are provided regardless of percent through-wall depth and the voltages provided correspond to the bobbin coil.
Table 5: A 1 R23 Foreign Object Wear Indications
                                                            +Point    Axial      Circ
                                                + Point SG    Row    Col      Location (Voltage)
Depth    Extent    Extent (3/4TW)        (in)    (deg) 1A    96    107    TSH+0.12          0.15        12      0.31      49 1A    98    107    TSH +0.12          0.15        12      0.26      54 1A    97    108    TSH +0.22          0.16        12      0.26      55 1A    17    138    TSH+0.17          0.24        16      0.20      60 1A    20    139    TSH +0.04          0.10          9      0.17      66 1B    98    47    TSH +0.00          0.27        17      0.17      43 1C    18      3    TSC +1.08          0.11        13      0.22      45 1C    20      3    TSC+0.17          0.15        14      0.17      54 1C    18      5    TSC +2.22          0.51        42      0.25      66 1C    93    54    TSH +0.12          0.35        19      0.36      45 1C      6    59    TSC +0.26          0.26        23      0.28      62 1C      3    64    TSC +0.22          0.41        34      0.28      72 1C      2    65    TSC +0.12          0.37        31      0.28      74 1C      1    72    TSH +0.28          0.06          6      0.11      35 1C      5    72    TSH +0.28          0.61        25      0.22      66 1C      2    73    TSH +0.25          0.08          8      0.14      43 E1 - 7 of 25
 
Enclosure 1
: 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 Braidwood Unit 1 SG program. The tube degradation detected during the A 1 R23 inspection was due to fan wear, lattice grid wear and foreign object wear at the tubesheet. The deepest indication for each mechanism met condition monitoring analytically as shown in Figures 2, 3 and 4a and 4b below. The margin to the structural and condition monitoring limit curve for each detected wear indication can be determined from Figures 2, 3 and 4a and 4b. The CM limit curves include uncertainties for material properties, NOE depth sizing, and the burst pressure relationship. Because the deepest flaws have a depth less than the conservatively determined CM limit for all degradation mechanisms, the structural integrity performance criterion was met for the operating interval prior to A 1 R23. A summary of the CM results from A 1 R23 as compared to the predictions from the most recent prior inspection (A 1 R 19) is provided in Table 6.
E1 - 8 of 25
 
Enclosure 1 Figure 2: Condition Monitoring Results for Fan Bar Wear Bobbin. ETSS H-9-6004 3 i
E1 - 9 of 25
 
Enclosure 1 Figure 3: Condition Monitoring Results for Lattice Grid Wear Bobbm. ETSS H,96004 3 Ax,ai Extent fine hos)
E1 - 10 of 25
 
Enclosure 1 Figure 4a: Condition Monitoring Results for Foreign Object Wear (ETSS 27902.1)
Army, ET5S H-27902.l s
E1-11of25
 
Enclosure 1 Figure 4b: Condition Monitoring Results for Foreign Object Wear (ETSS 21.998.1)
Array, ETSS H-21998.l E1 - 12 of 25
 
Enclosure 1 Table 6: Comparison of Prior QA Projections to As-Found Results Parameter                      A 1 R23 Projection          A1R23 As-Found Inspection Interval              5.83 EFPY (from A 1R19)          5.734 EFPY Fan Bar Wear Maximum Depth                      34.8 3/4TW                    16%TW Lattice Grid Wear Maximum Depth                  28.0 3/4TW                    11 3/4TW Foreign Object Wear Maximum Depth                < 57.6 3/4TW                  42 3/4TW Tube-to-tube Wear                        31.7%TW                      None The most severe indication in A 1R23 had an estimated depth of 42% TW from the plus-point probe exam. Since foreign object wear is a random event and there had only been 2 of 7 new foreign object wear indications that required to be plugged, one tube for being over the 40% Tech Spec limit and the other tube having the part remaining. There was no prediction for new foreign object wear made during the prior inspection in A 1R 19.
Because volumetric wear indications will leak and burst at essentially the same pressure, 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 A 1 R23. Because tube integrity was demonstrated analytically, in-situ pressure testing was not required nor performed during A 1 R23. There were no tube pulls planned or performed during A 1 R23.
: 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.
Tables 7a & b provides the number of tubes plugged for each degradation mechanism detected, location, and reason for plugging during A 1R23 As a result of the A 1 R23 SG inspections, performed in accordance with TS 5.5.9.d, the modes of tube degradation found were Fan Bar wear, Lattice Grid wear, and secondary side foreign object (FO) wear.
One tube (1 C SG R18-C5) was plugged for FO Wear for exceeding the tech spec criteria of 40% TW. The other tube (1 C SG R93-C54) was plugged for both FO Wear (19% TW) and an Eddy Current possible loose part (PLP) indication which could not be visually inspected.
In addition, 12 tubes were plugged as a preventative measure when the FO could not be removed or properly characterized from visual inspections. Inspection results justified a 5-cycle inspection interval with no adverse consequences for all four SGs.
E1 - 13 of 25
 
Enclosure 1 Table 7a: Number of Tubes Plugged, location and Reason for Each Degradation Mechanism in A1 R23 (TS 5.6.9.c.4)
SG        Row          Col      Location          Reason for Plu~rninq 1C        18            5        TSC +2.22        Exceeded TS criteria of > 40%
1C        93            54      TSH +0.12        Tube had FO wear and ECT PLP present 1C        94            53      TSH              Preventatively plugged 1 1C        91            54      TSH              Preventatively plugged 1 1C        93            54      TSH              Preventatively plugged 1 1C        95            54      TSH              Preventatively plugged 1 1C        92            55      TSH              Preventatively plugged 1 1C        94            55      TSH              Preventatively plugged 1 1C        109          60      TSH              Preventatively plugged 2 1C        111          60      TSH              Preventatively plugged 2 1C        113          60      TSH              Preventatively plugged 2 1C        108          61      TSH              Preventatively plugged 2 1C        110          61      TSH              Preventatively plugged 2 1C        112          61      TSH              Preventatively plugged 2 Notes:
1: All bounding tubes related to tube 93-54 were No Degradation Detected (NOD) and no PLPs with ECT. Visual inspections could not be performed on this location.
2: No wear, but FO was visually seen, but unable to confirm description Table 7b: Number of Tubes Plugged for Each Degradation Mechanism in A1R23 (TS 5.6.9.c.4)
Deqradation Mechanism          1ASG      18 SG    1CSG        1D SG    Total Fan Bar Wear              0          0          0        0        0 Lattice Grid Wear          0          0          0        0        0 Foreiqn Object Wear          0          0          2        0        0 Preventative              0          0        12        0        0 Total Pluqqed during A 1R23      0          0        14        0        14
: 8. The repair methods utilized, and the number of tubes repaired by each repair method (section 5.6.7.c.5).
Not Applicable
: 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). The effective full power months of operation permitted for the current operational assessment.
E1 - 14 of 25
 
Enclosure 1 Based on application of conservative U-bend support structure (fan bars) and lattice grid wear growth rates and foreign object susceptibility, the condition of the Braidwood Unit 1 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 inspection in the Spring of 2030 (A 1R28).
Fan Bar Wear Operational Assessment (OA)
For the Fan Bar OA, the Mixed Arithmetic/Simplified Statistical method from Section 8 of Reference 5 was used. Using this method, a worst-case end-of-cycle (EOC) depth was projected by applying NOE uncertainties and a growth allowance to the deepest flaw returned to service. This projected EOC depth is then compared to an allowable EOC depth which is calculated using a Monte Carlo analysis which incorporates uncertainties in the burst pressure relationship and material properties.
The deepest fan bar indication returned to service was 16% TW. The NOE sizing parameters for ETSS 96004.3 are a slope of 0.97, an intercept of 2.50, and a standard error of 3.10.
Using the slope and intercept, a best estimate real depth of 18.0% TW (0.97 x 16 + 2.5) is obtained for an indication with a measured depth of 16% TW.
The standard error of 3.10 from ETSS 96004.3 is the technique uncertainty. Adjusting this value upward to an upper 95th percentile gives an N DE uncertainty of 5.1 % TW (3.10 x 1.645). Adding this uncertainty to the best estimate value of 18.0% TW from the previous paragraph yields a bounding real depth of 23.1 % TW (18.0 + 5.1) returned to service.
This hypothesized real depth of 23.1 % TW must then be grown at an upper 95th growth rate for the next inspection interval. For this operational assessment, wear at support structures is being evaluated for five fuel cycles of 1.5 EFPY each The highest upper 95th percentile growth rate for any steam generator over the last two inspection was 0.93% TW per EFPY.
Since the growth rates are so low for fan bar wear at Braidwood Unit 1, a conservative growth rate of 1.5% TW per EFPY was used in the operational assessment. This value conservatively bounds the maximum growth rate from the last two operating intervals. Applying a growth of 7.3% TW (1.0 x 7.3) gives a bounding real depth at the end of the upcoming inspection interval of 34.1 % TW (23.1 + 7.3). For a flaw with an assumed bounding length of 1. 7 inches, the allowable structural depth at the end of the upcoming inspection cycle is 57.1 % TW. Since the projected depth of 30.4% TW is less than 57 .1 % TW, there is reasonable assurance that structural integrity will be maintained for Fan Bar wear for the next five cycles of operation.
Lattice Grid Wear OA For lattice grid wear, the OA was performed in a manner similar to what was done for fan bar wear. Unlike fan bar wear, however, there is too little data from which to calculate a reliable upper 95 th percentile growth rate. There were eleven (11) lattice grid wear indications reported during the A 1R23 outage. The deepest indication measured 11 % TW with a bobbin probe One (1) of these indications were newly reported, not present in past history. The largest growth was 11 % TW over an operating interval of 5.733 EFPY giving a maximum growth rate of 0.52%TW per EFPY. Similar to fan bar wear, since the growth rates for lattice grid wear are so low, growth rate of 1.0% TW per EFPY will be used for this operational assessment.
E1 - 15 of 25
 
Enclosure 1 The lattice grid flaws are typically short and occur at one edge of a lattice grid. However, since length measurements were not made for these indications, a bounding flaw length of 3.5 inches from the longest lattice grid intersection of 3.15 inches was assumed. This length was obtained from the "high bar" lattice grids which was from the maximum lattice grid length of 1.01" sized during A 1R23. This is very conservative based on the flaw lengths observed in previous outages Using the same Mixed Arithmetic/Simplified Statistical method Section 8 of Reference 5 and the same bobbin ETSS (96004.3), a best estimate real depth of 13.2% TW (0.97 x 11 + 2.5) is obtained for a measured depth of 11 %TW. Applying upper 95 th percentile NOE uncertainties yields a bounding real depth of 18.3% TW (13.2 + 1.645 x 3.1) returned to service. Further applying a growth rate of 1.0% TW per EFPY (as discussed above) over 7.3 EFPY gives a projected real EOC depth of 25.6% TW (18.3 + 1.0 x 7.3). For a flaw with an assumed bounding length of 3.5 inches, the allowable structural depth at the end of the upcoming inspection cycle is 56.0% TW. Since the projected depth of 25.6% TW is less than 56.0% TW, there is reasonable assurance that structural integrity will be maintained for lattice grid wear for the next five cycles of operation.
Tube Wear from Existing, Remaining, and New Foreign Objects OA Largest depth indication detected during A 1R23, was a 42% TW. All of the foreign objects that were classified as potentially causing tubes wear, Priority 1, were removed from the steam generators or tubes preventively plugged around the object(s). The remaining objects were classified as Priority 3, not potentially causing tube wear based on their composition, size and/or low-flow location. This included objects such as sludge rocks and tube scale which are considered benign based on no known history of causing tube wear. A summary of the OA results predicted at the next inspection (or longer) is provided in Table 8.
Table 8: Comparison of OA Projections at Next SG Inspection to Structural Limits Degradation Mechanism          Maximum depth(%) Predicted            Structural limit (wear)                        at Next Inspection                    depth(%)
Fan Bar U-bend support        30.4                                  57.1 Lattice Grid support          25.6                                  56.0 Existing FO Wear              34.0                                  59.0-66.3% (technique and length dependent)
Remaining FOs                  < 20%TWWear                          60-75% (technique and length dependent)
New FOs                        Limiting flaw won't challenge        60-75% (technique and structural or leakage integrity      length dependent) after 5 operating cycles
: 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 before and after the A 1 R23 outage and the percentage of tubes currently plugged (total and effective). No sleeves have been installed in Braidwood Unit 1.
E1 - 16 of 25
 
Enclosure 1 Table 9: Tube Plugging to Date (Number and Percentage per SG) (TS 5.6.9.e) 1ASG      18 SG      1C SG      1D SG      Total Total Pluqqed prior to A 1R23        32        40          16          1        89 Total Plugged during A 1R23          0          0          14          0          14 Total Stabilized during A 1R23        0          0            1          0          1 Total Pluqqed throuqh A 1R23          32        40          30          1        103 Total Percent Plugged through 0.48%      0.60%        0.45%      0.02%    0.39%
A1R23
: 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 Scope:
* Sludge lancing in all four SGs including "post sludge lance" Foreign Object Search and Retrieval (FOSAR)
* Feedring Inspection (1A SG)
* Steam Drum Internal Inspections (1A & 1B SG)
* Upper Bundle Inspection ( 1A SG)
Secondary Side Visual Inspections of Tubesheet and FOSAR Secondary side tubesheet visual inspections were performed following sludge lancing activities in all four SGs. High flow regions of the annulus, no tube lane and periphery (6-8 tubes deep) were visually inspected for foreign material. Additionally, eight columns for the full depth of the tube bundle interior ("kidney" region) were evaluated for sludge lancing effectiveness and sludge accumulation.
Secondary side foreign object search and retrieval (FOSAR) inspections at the tubesheet were performed in all four SGs. This included visual examination of tube bundle periphery tubes from the hot leg and cold leg annulus and center no tube lane. Twenty-one (21) foreign object locations all of which were assumed metallic, were identified by visual inspections and/or eddy current examinations and are summarized in Table 10 Foreign object wear is the primary degradation mechanism of concern at Braidwood-1 based on previous history. In A 1R23, one tube was plugged for FO Wear of 42% TW, one tube was plugged for FO wear of 19% TW with an ECT PLP still present, and 12 other locations were plugged as a preventative measure when the FO could not be removed or properly characterized from visual inspections.
Visual inspections included both the annulus and no-tube lane at the top of the tubesheet in all four steam generators. These visual inspections included looking into the tube bundle at all peripheral and no-tube lane locations. The eddy current examinations included tubesheet array probe inspections of all tubes in the high-flow regions at the periphery and no-tube lane on both the hot (~3800 tubes) and cold sides (~2900 tubes) in all four steam generators. With these extensive inspections and subsequent object removal, there is reasonable confidence that no object capable of causing significant tube degradation remains in the tube bundle adjacent to in-service tubes.
E1 - 17 of 25
 
Enclosure 1 A total of 14 metallic or potential metallic foreign objects within the tube bundle in SGs A, B, and C were not removed during A 1 R23 and are included in the total list of all foreign objects remaining in the SGs in Table 10.
A top of tubesheet in-bundle visual inspection in a sample of tube columns was also performed in each SG for the purpose of assessing and trending the level of hardened deposit buildup in the kidney region.
Based upon the extensive secondary side inspections, object removals, and engineering assessments performed during the 1AR23 outage, there is reasonable assurance that during the next five operating cycles foreign object wear will not exceed the structural and leakage integrity performance criteria.
Table 10: Foreign Object Summary Affected                                                                  Status SG                  Location  Ref ID              A1R23 Disposition                          Material Tubes NIA                                    Object was removed.
Below                          Nearest adjacent tubes were NOD with      Retrieved    Gasket 1A                    TSC      A001 Manway                                            ECT Hand hole                        No further actions required in A 1R23.
Object identified with visual inspections R104-C73                            and was removed. All affected and      Retrieved 1A                    TSC      A003                                                            Gasket R105-C72                          bounding tubes are NOD with ECT No further actions required in A 1R23.
Object identified with visual inspections R 104-C79                      was removed. All affected and bounding    Retrieved 1A                    TSC      A004                                                            Gasket R105-C78                              tubes are NOD with Bobbin.
No further actions required in A 1R23.
Acceptable to remain in the SG. All Wire Bristle R57-C134                      affected and bounding tubes are NOD with    Remains or Thin Fiber R58-C133                          ECT Object is extremely thin wire or 1A                    TSH      A005                                                            (1.0L x R59-C132                      possibly fibrous material and not expected 0.001 D)
R60-C133                                to cause wear on a tube.
No further actions required in A 1R23.
Acceptable to remain in the SG. All Wire Bristle affected and bounding tubes are NOD with    Remains or Thin Fiber R97-C32                          ECT. Object is extremely thin wire or 1A                    TSH      A006                                                            (2 0L x R98-C33                      possibly fibrous material and not expected 0.001 D) to cause wear on a tube.
No further actions required in A 1R23.
Acceptable to remain in the SG. All Wire Bristle affected and bounding tubes are NOD with    Remains or Thin Fiber R83-C22                          ECT. Object is extremely thin wire or 1A                  TSH      A007                                                            (2.0L X R84-C23                      possibly fibrous material and not expected 0.001 D) to cause wear on a tube.
No further actions required in A 1R23.
Acceptable to remain in the SG. All Wire Bristle affected and bounding tubes are NOD with    Remains or Thin Fiber R77-C18                          ECT Object is extremely thin wire or 1A                  TSH      A008                                                            (2.0L X R78-C19                      possibly fibrous material and not expected 0.001 D) to cause wear on a tube. No further actions required in A 1R23.
E1 - 18 of 25
 
Enclosure 1 Affected                                                              Status SG          Location Ref ID                A1R23 Disposition                        Material Tubes R71-C72    TSC              Object was removed. All affected and 1A R72-C71            A009      bounding tubes are NOD with Bobbin. Retrieved    Gasket R73-C72                      No further actions required in A 1R23.
Object identified with visuals during R103-C74                    retrieval of A003 and was removed. All  Retrieved 1A R104-C73    TSC    A010  affected and bounding tubes are NOD with                  Gasket R10S-C74                                      Bobbin.
No further actions required in A 1R23.
Legacy 2016 R81-C22            A011      Object was confirmed unchanged from      Remains  metallic weld R82-C23            (A001                      A1R19.                                slag 1A            TSC R83-C22            from    All bounding tubes are NOD with ECT.              (1SLx0.1W R84-C23            1R19)      No further actions required in A 1R23.              x 0.1H)
Object was identified visually and removed R11S-CS8 from the SG. All affected and bounding    Retrieved      Wire 1B R116-CS9    TSC    B001 tubes are NOD with ECT.
R117-CS8 No further actions required in A 1R23.
Acceptable to remain in the SG. All affected and bounding tubes are NOD with    Remains R116-C8S                      ECT. Object is extremely thin wire or            Wire Bristle 1B            TSH    B003 R117-C86                  possibly fibrous material and not expected            or Thin Fiber to cause wear on a tube.
No further actions required in A 1R23.
Object confirmed with visuals during retrieval of B001 All affected and  Remains      Gasket bounding tubes are NOD. Acceptable to                  (-2 0L x CS8-S9 1B            TSC    BOOS  remain in the SG without plugging based                012SWx R27-28 on evaluation performed in Section Error!                0.031H Reference source not found.
No further actions required at A 1R23.
Visually confirmed as a gasket Part was Gasket 1C  C60-61    TSC    C004                removed from the SG.        Retrieved R99-104                      No further actions required in A 1R23.
Visually confirmed as unchanged from                  Legacy A1R19. Affected and bounding tubes are    Remains      metallic coos                    NOD with ECT.                        snare collar 1C  R3-C48    TSH    (1R19 Acceptable to remain in the SG without                (0.14L x C001) tube plugging                          0.11Wx No further actions required at A 1R23                0.3H)
Legacy 2016 Visually confirmed as unchanged from Remains      metallic A 1R 19. Affected and bounding tubes are C006                                                            gasket NOD with ECT.
1C  R44-C7S    TSC    (1R19                                                            (1 SL x Acceptable to remain in the SG without C004)                                                          0188Wx tube plugging.
0.0SH)
No further actions required at A 1R23 Affected                        Object was visually identified from R109-C60                          periphery but unable to confirm    Remains Potential R110-C61                    descriptions. All affected and bounding White Object R 111-C60                      tubes are NOD. Object evaluated for (assumed 1C            TSH    C007      potential to cause wear and results in Gasket 2L x Bounding                    projected depths at A 1R23 in excess of 0.12SWx R108-C61                  40% TW. Plug and stabilize affected and 0.031 H)
R112-C61                  bounding tubes 108-61, 112-61, and 113-R113-C60                                    60 at A1 R23.
E1 - 19 of 25
 
Enclosure 1 Affected                                                                  Status SG                  Location  Ref ID              A 1 R23 Disposition                      Material Tubes ECT identified PLPs with wear in three R18-C3                          tubes (13%TW in 18-3, 42%TW in 18-5,    Retrieved R18-C5                          and 14% TW in 20-3). Visual inspections            ECT PLP w/
R20-C3                COOS I      confirmed two objects which were                    Wear 1C                  TSC R22-C3                C009    removed from the SG. Array retests after            Gasket and R23-C4                                removal confirmed no PLPs.                  Weld Splatter R25-C4                            Tube 18-5 to be plugged in A1R23, remaining tubes to be left in-service.
Visually confirmed as unchanged from                  Legacy A1R19. Affected and bounding tubes are    Remains      metallic 1R19                  NOD with ECT                            gasket 1C    R33-C102      TSH coos      Acceptable to remain in the SG without            (0.5L x 0.2W tube plugging.                          x 0.2H)
No further actions required at A 1R23 Visually confirmed as unchanged from                  Legacy A1R19. Affected and bounding tubes are    Remains  metallic wire 1R19-                  NOD with ECT.                          (0.92L X 1C    R33-C102      TSH C009      Acceptable to remain in the SG without              0188Wx tube plugging.                          0.5H)
No further actions required at A 1R23 ECT identified PLPs with wear in one tube (19%TW in R93-C54). All bounding tubes    Remains were NOD and no PLPs with ECT. Visual New ECT FO 1C    R93-C54      TSH        NIA  inspections could not be performed on this w/PLP location.
Affected tube R93-C54 and all 1-tube bounding tubes plugged in A 1R23.
Visual inspection of the Feedring, upper tube bundle and the lattice grids During the Feedring inspections in the 1A SG, no anomalous structural conditions or foreign objects were observed. Additionally, no erosion or component degradation was identified.
During visual inspections in the 1A SG of the lattice grids at the uppermost (9th) support location for the hot leg and cold leg some deposit accumulation was identified on the hot leg side at the lattice grids and on the tube surfaces. Deposit loading on the tube and structure surfaces, and within lattice openings was relatively minor in the regions examined. No degradation was noted.
Steam drum visual inspections Steam drum visual inspections were performed in the 1A and 1B SGs. No evidence of foreign material, degradation or structural distortion was observed in the steam drum. The primary and secondary moisture separators were in good condition. The inlet vanes, outlet ports, vent holes, and skimmer vanes internals of 14 secondary moisture separators internals and internals of 6 primary moisture separators in each SG were visually inspected for degradation and none was found.
No repairs were required for the secondary side inspection, and it was concluded that a 5-cycle inspection interval was justified with no adverse consequences for all 4 SGs.
: 12. The scope, method, and results of secondary-side cleaning performed in each SG Prior to the secondary side FOSAR inspections, sludge, scale, foreign objects, and other deposit accumulations at the top of the tubesheet were removed as part of the top of E1 -20 of25
 
Enclosure 1 tubesheet high pressure water lancing process. The weight of deposits removed from each SG by this cleaning process is provided in Table 11. Given Braidwood Unit 1 had operated 4 cycles from the last sludge lancing in A 1R 19, the amount of accumulation per SG was expected. A visual inspection of the upper lattice grids showed no significant deposit accumulation and no conditions that would adversely impact tube integrity.
Table 11: A 1R23 SG Deposit Removal Weights
                                                                                                --~1 SG                                              Weight SG1A                                            21.25 lbs SG1B                                            14.75 lbs SG1C                                            17.25 lbs SG1D                                            37.25 lbs I                    All SGs                                          90.5 lbs
: 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 previously installed tube plugs (89) were visually inspected for signs of degradation and leakage.
The tube-to-tubesheet welds were visually inspected during eddy current. No degradation or anomalies were found.
SG Channel Head Bowl Visual Inspections Each SG hot and cold leg primary channel head was visually examined in accordance with the recommendations of Westinghouse NSAL 12-01 and NRC IN 2013-20 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 to channel head weld was identified.
References
: 1. CEG letter to NRC, RS-22-086, Application to Revise Technical Specifications to Adopt TSTF-577, "Revised Frequencies for Steam Generator Tube Inspections",
dated August 10, 2022 (ML22222A068)
: 2. CEG letter to NRC, RS-23-050, Application to Revise Technical Specifications to Adopt TSTF-577, "Revised Frequencies for Steam Generator Tube Inspections" (ML23143A136)
: 3. NRC letter to CEG," BRAIDWOOD STATION, UNIT NOS. 1 AND 2 - ISSUANCE OF AMENDMENTS 233 AND 233 RE: ADOPTION OF TSTF-577, "REVISED FREQUENCIES FOR STEAM GENERATOR TUBE INSPECTIONS," REVISION 1 (EPID L-2022-LLA-0115)",
dated July 26, 2023 (ML23188A129)
: 4. Constellation Generation letter (BW230019) to NRC, "Braidwood Station, Unit 1 Steam Generator Tube Inspection Report for Refueling Outage 23," dated April 5, 2023 (M L23095A 129)
: 5. Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines, Revision 5, EPRI, Palo Alto, CA, December 2021 (3002020909)
E1 - 21 of 25
 
Enclosure 1 ATTACHMENT A - Fan Bar Wear Indications (SG 1A)
SGID INSPDATE  ROW  COL PER    VOLTS    DEG CHN LOCN INCH1  PDIA PTYPE 1A  10/1/2022  31    4  3      0.21    0  P2  F05  1.06 0.56 CBAFN 1A  10/1/2022  68  49  5      0.24    0  P2  F04  0.79 0.56 CBAFN 1A  10/1/2022  71  62  5      0.28    0  P2  F04  -1.19 0.56 CBAFN 1A  10/1/2022  63  70  5      0.29    0  P2  F05  0.5  0.56 CBAFN 1A  10/1/2022  77  84  2      0.15    0  P2  F05  -0.98 0.56 CBAFN 1A  10/1/2022  84  87  6        0.31    0  P2  F05  -0.8 0.56 CBAFN 1A  10/1/2022  99  90  11      0.57    0  P2  F05  -1.24 0.56 CBAFN 1A  10/1/2022  109  90  8      0.43    0  P2  F05  -1.23 0.56 CBAFN E1 - 22 of 25
 
Enclosure 1 ATTACHMENT A - Fan Bar Wear Indications (SG 1 B)
SGID INSPDATE  ROW  COL PER  VOLTS    DEG CHN LOCN INCH1  PDIA PTYPE 1B  10/1/2022  42  137  7      0.37    0  P2  F06  0.94 0.56 CBAFN !
1B  10/1/2022  45  130  5      0.24    0  P2  F05  -1.28 0.56 CBAFN ;
1B  10/1/2022  52  63  4      0.2      0  P2  F05    1.2 0.56 CBAFN 1B  10/1/2022  57  42  6      0.3    0  P2  F05  -1.73 0.56 CBAFN 1B  10/1/2022  60  73  7      0.38    0  P2  F05  -1.9 0.56 CBAFN 1B  10/1/2022  65  70  4      0.23    0  P2  F06  -1.65 0.56 CBAFN 1B  10/1/2022  68  65  3      0.19    0  P2  F05  0.87 0.56 CBAFN 1B  10/1/2022  71  62  3      0.19    0  P2  F04  0.83 0.56 CBAFN 1B  10/1/2022  73  102  8      0.36    0  P2  F05  1.18 0.56 CBAFN 1B  10/1/2022  76  73  9      0.47    0  P2  F05  -0.86 0.56 CBAFN 1B  10/1/2022  78  57  8      0.48    0  P2  F07  -1.38 0.56 CBAFN 1B  10/1/2022  80  71  3      0.15    0  P2  F05  1.12 0.56 CBAFN 1B  10/1/2022  82  69  5      0.33    0  P2  F06  -1.37 0.56 CBAFN 1B  10/1/2022  82  79  5      0.25    0  P2  F06    1.9 0.56 CBAFN 1B  10/1/2022  88  69  5      0.27    0  P2  F08  1.04 0.56 CBAFN 1B  10/1/2022  100  57  7      0.42    0  P2  F07  1.77 0.56 CBAFN 1B  10/1/2022  107  68  7      0.38    0  P2  F05  1.49 0.56 CBAFN 1B  10/1/2022  111  70  5      0.27    0  P2  F06  -1.32 0.56 CBAFN E1 - 23 of 25
 
Enclosure 1 ATTACHMENT A - Fan Bar Wear Indications (SG 1C)
SGID INSPDATE  ROW  COL PER    VOLTS    DEG CHN LOCN INCH1  PDIA PTYPE 1C  10/1/2022  35  70  4      0.37    0  P2  F05  1.85 0.56 CBAFN 1C  10/1/2022  54  79  7      0.31    0  P2  F06  0.63 0.56 CBAFN 1C  10/1/2022  55  56  7      0.34    0  P2  F05  1.85 0.56 CBAFN 1C  10/1/2022  57  78  9      0.51    0  P2  F06  0.71 0.56 CBAFN 1C  10/1/2022  59  68  4      0.22    0  P2  F05  0.61 0.56 CBAFN 1C  10/1/2022  66  61  11      0.62    0  P2  F07  1.81 0.56 CBAFN 1C  10/1/2022  74  63  4      0.17    0  P2  F06  -1.28 0.56 CBAFN 1C  10/1/2022  74  75  5      0.26    0  P2  F05  -1.14 0.56 CBAFN 1C  10/1/2022  76  65  4      0.18    0  P2  F05  1.32 0.56 CBAFN 1C  10/1/2022  77  66  6      0.3    0  P2  F05  -0.54 0.56 CBAFN 1C  10/1/2022  77  68  12      0.66    0  P2  F05  -0.96 0.56 CBAFN 1C  10/1/2022  79  66  7      0.33    0  P2  F05  -0.89 0.56 CBAFN 1C  10/1/2022  79  94  12      0.66    0  P2  F06  -1.18 0.56 CBAFN 1C  10/1/2022  80  63  7      0.33    0  P2  F06  -1.45 0.56 CBAFN 1C  10/1/2022  90  79  14      0.83    0  P2  F06  1.51 0.56 CBAFN 1C  10/1/2022  91  72  9      0.48    0  P2  F06    0.7 0.56 CBAFN 1C  10/1/2022  92  57  8      0.39    0  P2  F05  1.44 0.56 CBAFN 1C  10/1/2022  92  69  14      0.94    0  P2  F05  -0.9 0.56 CBAFN 1C  10/1/2022  93  78  6      0.33    0  P2  F05  -0.7 0.56 CBAFN 1C  10/1/2022  94  63  8      0.38    0  P2  F05  -1.76 0.56 CBAFN 1C  10/1/2022  94  85  7      0.39    0  P2  F04  0.69 0.56 CBAFN 1C  10/1/2022  95  58  8      0.39    0  P2  F05  -0.64 0.56 CBAFN 1C  10/1/2022  96  57  10      0.51    0  P2  F05  0.68 0.56 CBAFN 1C  10/1/2022  97  86  9      0.46    0  P2  F05  1.21 0.56 CBAFN 1C  10/1/2022  97  88  5      0.23    0  P2  F05  1.54 0.56 CBAFN 1C  10/1/2022  98  59  9      0.45    0  P2  F05  1.21 0.56 CBAFN 1C  10/1/2022  99  84  7      0.31    0  P2  F07  0.85 0.56 CBAFN 1C  10/1/2022  100  75  7      0.35    0  P2  F05  -1.55 0.56 CBAFN 1C  10/1/2022  101  60  9      0.45    0  P2  F05  1.63 0.56 CBAFN 1C  10/1/2022  101  84  9      0.43    0  P2  F07  0.73 0.56 CBAFN 1C  10/1/2022  102  61  10      0.55    0  P2  F05  1.01 0.56 CBAFN 1C  10/1/2022  103  86  9      0.47    0  P2  F05  -0.65 0.56 CBAFN 1C  10/1/2022  104  63  8      0.39    0  P2  F05  1.53 0.56 CBAFN 1C  10/1/2022  105  72  10      0.52    0  P2  F03  -0.54 0.56 CBAFN 1C  10/1/2022  106  59  9      0.44    0  P2  F05  1.02 0.56 CBAFN 1C  10/1/2022  107  70  8      0.39    0  P2  F05  1.89 0.56 CBAFN 1C  10/1/2022  107  76  5      0.23    0  P2  F05  -1.39 0.56 CBAFN 1C  10/1/2022  107  80  6      0.32    0  P2  F05  1.86 0.56 CBAFN 1C  10/1/2022  111  88  5      0.21    0  P2  F08  1.85 0.56 CBAFN E1 - 24 of 25
 
Enclosure 1 ATTACHMENT A - Fan Bar Wear Indications (SG 1D)
SGID INSPDATE  ROW  COL PER VOLTS        DEG CHN LOCN INCH1  PDIA PTYPE 1D  10/1/2022  35  138  8      0.35      0  P2  F05  0.99 0.56 CBAFN 1D  10/1/2022  45  56  5      0.18      0  P2  F06  -0.99 0.56 CBAFN 1D  10/1/2022  50  57  5      0.2      0  P2  F05  1.25 0.56 CBAFN 1D  10/1/2022  72  71  5      0.3      0  P2  F06  0.91 0.56 CBAFN 1D  10/1/2022  81  70  11      0.56      0  P2  F06  -1.61 0.56 CBAFN 1D  10/1/2022  85  68  10      0.6      0  P2  F07  1.43 0.56 CBAFN 1D  10/1/2022  85  70  16      1.05      0  P2  F06  -1.38 0.56 CBAFN 1D  10/1/2022  86  67  8      0.36      0  P2  F06  0.66 0.56 CBAFN 1D  10/1/2022  86  69  10      0.63      0  P2  F07  -1.56 0.56 CBAFN 1D  10/1/2022  87  64  8      0.49      0  P2  F06  1.26 0.56 CBAFN 1D  10/1/2022  93  70  11      0.69      0  P2  F06  -1.08 0.56 CBAFN 1D  10/1/2022  95  68  9      0.43      0  P2  F05  -1.26 0.56 CBAFN 1D  10/1/2022  95  68  9      0.44      0  P2  F06  1.21 0.56 CBAFN 1D  10/1/2022  96  69  8      0.4      0  P2  F08    0.7 0.56 CBAFN 1D  10/1/2022  97  72  8      0.49      0  P2  F06  0.51 0.56 CBAFN 1D  10/1/2022  97  74  9      0.54      0  P2  F08  -0.86 0.56 CBAFN 1D  10/1/2022  99  64  7      0.35      0  P2  F05  -1.32 0.56 CBAFN 1D  10/1/2022  100  67  3      0.21      0  P2  F08  1.32 0.56 CBAFN 1D  10/1/2022  103  68  7      0.33      0  P2  F07  -1.28 0.56 CBAFN 1D  10/1/2022  104  53  11      0.56      0  P2  F05  1.36 0.56 CBAFN 1D  10/1/2022  104  77  5      0.24      0  P2  F06  -1.58 0.56 CBAFN E1 - 25 of 25}}

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